Stuck at 400 ELO and I've been playing for a year.

Wait another year. Ive been playing for around 2 yrs and am like 600-650 so relax, take it slow, do puzzels, watch the lessons and youll be fine.

Think twice before each move.

Learn other kinds of openings and when you face them in a game, you're prepared... Best of all, learn the endgame, when the position is equal, use opposition and sacrifice pawns to create a pass pawn

dont play the sicilian even intermediates cant understand it play the london or the ponziani or the scotch

I will do that sometimes seems like good advice.

Just try not to blunder and let your opponent make mistakes, around the move 25-30 for sure they will have blunder something at this point

Clear your head out of ego and then play.

(Always calculate like 2-3 moves ahead)

You can find your opponent's threats and find effective ways to stop them.

And if you are winning, don't be over confident.

Btw watch gothamchess on the new road to gm series

Lots of 400 rated people already know how to defend scholars mate and fried liver. If it happens so many times to them, they learn how to defend it and start counter attacks

Today I am > 1000 on Rapid Games 10 minutes and I remember perfectly what I did to achieve 500. I spent three months getting from my minimum 230 to 500.

You must have a plan, here is the plan I used to arrive at 500.

1. Subscribe to Chess.com. I subscribed 4 years ago as a Gold member. At that time, Gold members could have unlimited game revision. Unlimited game review is the most important feature. Today the membership costs more and if you don't want to pay the membership use Lichess.org. However, on Lichess.org that players rating is higher, for example I am > 1400 there in Rapid games.

2. Play max 3 games a day but don't play when you are doing other stuff. Be concentrated on the game. Use the computer instead of the app on the phone. In front of a computer usually, people are more concentrated.

3. Play only Rapid for 10 minutes. It's a good compromise because a game lasts max 20 minutes and in max 1 hour you can play 3 games. Usually, you'll play less than 40 minutes. I started to play daily games only when I achieved to 1000 rating.

4. Review always all the 3 games and try to figure out the mistakes. In particular, try to avoid blunders in the future.

5. Learn well the rules. I know what you're thinking. At that time, I thought I knew the rules but I didn't. I didn't know the existence of en passant, long castle, stalemate, and much more.

6. Learn the basic principles of Chess. Conquer the center, develop fast, king safety. I know you heard this stuff a lot of times but at that time I lost a lot of games because I didn't develop fast.

7. Learn the opening principles. Max 2 pawn move, develop Knight before Bishop, never move the same piece before move 10, castle fast, develop the Queen to connect the Rooks. Once rooks are connected the development is finished. People with ratings < 500 lost a lot of games because they spent too much time developing.

8. To achieve 500 you need only these end games: Two Rooks vs King, Queen vs King, Rook vs King. There are other important end games but to achieve 500 you can avoid learning them and concentrate on more important stuff.. There are a lot of end games that still today after 4 years and more than 3000 games I never found in a game: Two Bishop vs King, Knight and Bishop vs King, Queen vs Rook. So for the moment, don't waste time with them.

9. Solve 25 puzzles a day.

10. If you want to play more than 3 games, play against a BOT. Use this rule. Start from the lowest-rated BOT and pass to the next only when you're able to beat it three consecutive times (at least one time with Black). With BOT don't use any time control. Consider that BOT are overrated, when I was < 500 I was able to beat 700 Elo Bots. Today I am > 1000 I am playing against Pable that is 1600. At the beginning, moving from one BOT to another requires only few days. Today I need months to beat a BOT three consecutive times. A lot of people are against BOT because they says they don't play like human. It's true. But I can guarantee you'll learn a lot from them.

11. Follow the free lessons on Chess.com. They will teach you everything you need. Especially the lesson that tells you to avoid hanging pieces. Notice that hanging pieces are all the pieces with more attackers than defenders. So whenever the opponent threatens your piece count the attacker and defender. My rule was three lessons a week.

12. Don't play traps. People follow Youtube Chess influencers to learn traps and win fast but this is the worst method to learn chess. I mean, you can learn trap but just to defend from them. For example, with a rating < 500 lot of people play the Winard attack to win fast. If you learn how to neutralize it you will win a lot of games. Sometimes people resign immediately as soon as they understand you know how to defend. Knight attack/Fried Liver Attack is another trap a lot of people with <500 ratings try a lot.

13. A lot of people suggest not learning any opening but just following the opening principle. I agree in part. I think you must study 1 opening well. For example, I studied the Italian Game and it is my main opening. All the other openings I learned them during game review. In this way, you learn only the opening you use in the game and if you only use game review you'll learn exactly the things you need. At the end, at very low rating you must know 5 or 6 moves of some opening like: Italian Game, Spanish Game, Scotch Game, Caro Kann, French and Petrov Defense.

14. Try to keep your body fit. I know this is not about Chess but when I exercise regularly also my mind works better. In my rating Statistics some periods I have a huge drop and usually this happens when I am sick or not physically OK.

15. Never never never resign. In the beginning, you must play as much as you can. Later when you chees comprehension will increase you'll realize that some games are lost and you can't do anything to save them. Before that time. Never resign.

16. Develop intuition. Chess is all about logic and calculation. But as you improve you will start to recognize some moves that are naturally good (ie. in the opening Nf3, Nc3, Nc6, Nf6, Bb4 are examples of natural move). When you start to acquire this knowledge you'll play fast and you'll never lost for time. Everytime you start to increase of 100 points you'll notice that you start losing a lot of game for time expiration. This is normal, you're play now with stronger people with an intuition more develop than yours. Be patient and after a while time will not be a problem anymore (at least until your next 100 increase).

17. Don't pay too much attention to the rating. The more you're concentrated on the rating the harder is to increase it. Just focus on learning, focus on your games, and enjoy the journey.

Always play the Sicilian

Reading stuff like Sucialian opening or Ponziani makes me feel awkward and incompetent here. I didnt learn any terms about opening or development. I just used to play as I was a kid. And 30 years later, one week ago I just logged in to entertain myself ‘coz I know the rules = I know how to play’. After a while I started to lose one after another, and entertainment all gone lol. Now I realize my opponents scrutinize all these things from books whilst I just play intuitively with occasional blunders once distracted. Long story short, please recommend a similar web-site where people are less serious about it, where I belong. Thanks!

https://www.chess.com/club/secret-chess-openings-1/join

Almost everything you wrote is wrong.

Of your last 10 games, you won 5 and lost 5. Completely normal, not "lose one after another".

Your opponents probably never read any books - if they did, they probably wouldn't be 800-rated. Even if they read a book, that's not something that tells you what move to play in your current game.

Knowing the name of an opening doesn't help either.

In chess.com there are people who take chess very seriously and there are some who don't. Low rated players (like those who you play against) usually don't. The same is true for all other chess websites. If you are looking for a site where everyone lets you win, good luck finding one.

To start your response with “everything I said is wrong” is not nice and doesnt present you as a friendly person. If you mean to offend but not to help - there is always a better option, which is ignore (you may also calculate your options in conversation as you do in chess). 
if you carefully read the message thread, there was a guy rated 400, who spoke about sicilian opening and who reads a lot to get better but got stuck at his level. My purpose os just fun, so I was looking for advice if there is a platform for rookies. I didnt mean to win all the time. But I guess my query is not addressed to you or to anyone who likes to turn a friemdly chat into an argument.

That was you who did that. I offered you my opinion, and you responded with a passive-aggressive personal attack immediately. Well, whatever, good luck finding your magical website.

I don't think so.

However, what does it matter if your opponents read books, watch videos, analyze games, etc.? There are many players here who are better than you, but also many of your level, and many weaker than you. And in fact, it doesn’t seem like you lose all the games. Whatever your level, you will always find an army of players like you, that's what matters.

Sometimes you win, sometimes you lose ( like all of us ), fun should be guaranteed.

im playing for 4 years and Im stuck at 1200

I checked 5 of your losses. They all have elementary mistakes, often in the first 5 or 6 moves. For example, you move your queen out too early, move pieces for a second time before developing all your pieces, move a rook pawn before developing pieces, hang pieces, miss free material, and so on. So you say you know the basics, but you don’t put them into practice. 

I would suggest trying a different approach to learning. Play over games of masters. Watch videos that explain all of the moves of a master. 

don’t worry about which opening to play. The best opening in the world won’t help if you make elementary mistakes in the first 5 moves.

Heheboy