is it better to learn One opening

Begiinners shouldn't learn openings at all.

You should just stick to opening principles for now. Pick some variation, just learn 3-5 moves of the variation and improvise from there sticking to principles.

Here you can read more on the opening principles and how to play the opening stage of the game:

https://www.chess.com/blog/nklristic/surviving-the-opening-first-steps-to-chess-improvement

I hope that you will find it instructive.

You're welcome.

I know its recommend beginners shouldn't study openings but you need to start somewhere. For white try the Italian Game. e4, nf3, bc4, then castle. After that develop your queenside and play opening principles. There are many you tube videos that explain the reasons behind the moves so I wont go through it here.

My "advice" regarding openings is simple. Try to play them and test in which of them the moves you think are the best, intuitively are either theory or acceptable. That way you can devote less time to wondering about openings per se and concentrate on other parts of the game. Using that method I discovered anything 1.e4 1.e5 does not come naturally to me. The same with 1.e4 c6 or even 1.e4 e6 with black. I also came to realize I can't really play the QGD with either colour and that I'm really bad when trying to play KIA setups. I'm also instinctively clueless about most lines in the Sicilian with either colour. So, using my account here as a masochist, those are my typical openings here. OTB or in serious games I'd never play any of that, because I know I'm going to make a bad move immediate after my theoretical knowledge has run out.

Chess Openings Resources for Beginners and Beyond...

https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond

Trying to learn and understand openings at your level serves no purpose.  You're not even understanding the very basics.  Start slow and keep it simple at first.

Opening Principles:

1. Control the center squares – d4-e4-d5-e5
2. Develop your minor pieces toward the center – piece activity is the key
3. Castle
4. Connect your rooks

Tactics...tactics...tactics...

The objective of development is about improving the value of your pieces by increasing the importance of their roles. Well-developed pieces have more fire-power than undeveloped pieces and they do more in helping you gain control.

Now we will look at 5 practical things you can do to help you achieve your development objective.

They are:

1. Give priority to your least active pieces.

• Which piece needs to be developed (which piece is the least active)
• Where should it go (where can its role be maximized)

2. Exchange your least active pieces for your opponent’s active pieces.
3. Restrict the development of your opponent’s pieces.
4. Neutralize your opponent’s best piece.
5. Secure strong squares for your pieces.

Don’t help your opponent develop.

There are 2 common mistakes whereby you will simply be helping your opponent to develop:

1. Making a weak threat that can easily be blocked
2. Making an exchange that helps your opponent to develop a piece

Pre Move Checklist:

1. Make sure all your pieces are safe.
2. Look for forcing moves: Checks, captures, threats. You want to look at ALL forcing moves (even the bad ones) as this will force you look at, and see the entire board.
3. If there are no forcing moves, you then want to remove any of your opponent’s pieces from your side of the board.
4. If your opponent doesn’t have any of his pieces on your side of the board, then you want to improve the position of your least active piece.
5. After each move by your opponent, ask yourself: "What is my opponent trying to do?"

I doubt you really need to learn openings, since 90% of the time, your opponents aren't going to play the "right" (book) move or any of the variations, like in the Sicilian, Ruy Lopez, or Kings Indian. If you really want to learn an opening, I suggest the Italian as white, and the Giuoco Piano as black (avoids annoying Ng5's), since it allows you to flexibly follow the opening rules.

Book-heavy openings can be a mental trap which leads to later stagnation.  Yes, it's important to understand the principles of the opening in general, and the basic premise of the opening you are playing, but the depth of book that is known increases with your skill level, and the amount of memorization required in openings like the GP, QGD, and Ruy Lopez and the Sicilian to contend at the higher levels generally increases faster than that.  Just as importantly, all of the book-heavy openings have anti-systems you need to know about.  If you play and of the 1. d4 Nf6 defenses with black, you need to prepare for the Trumpowsky, if you're a Sicilian player, Alapin is important to know.  If you play the GP or the Ruy Lopez, Petroff's Defense is a must-know.

I played the Ruy Lopez as white and the Sicilian as black for years, and I could beat anyone below 1500 or so almost effortlessly, but I couldn't even begin to challenge players about 1800, simply because they would know trap lines and anti-systems that I didn't.

Today, I am finally beginning to score against higher-level amateurs and Experts.  I play the Reti Opening as white (for which there is little book) and the Owen Defense as black (for which there is none at all that is of any use), the latter of which I had to spend quite some time to figure out (the one book suggestion from Staunton of an early c5 is wrong, the c-pawn stays home in order to restrain white's big pawn center).  It was not until I understood the strengths I possessed as a player (I have unusual comfort with tension, a fondness for the zwischenzug, and good tactical depth, all of which favors play with an open center) that I could choose openings which suited my playing style.  But making that next step meant abandoning my original opening repertoire.  That's the nature of the trap - a popular opening can become too comfortable to give up after a while, even as your own skills grow to the point where it is no longer suitable for best results.

Yeah I guess I know that now. But as white I always start with e4, and if black plays d6 then I feel like im always doing the wrong thing lol. But maybe its fine if I stay sort of concentrated on my own game as well and don't mess up major things. 

Great thanks! Nice lists. #5 of the last one I sometimes feel like my opponent is just trying to move pieces haha lol. But nice thanks will try to use this. 

nice will look at the black moves, thanks

Nice, its good that you're improving now then! Yes I think I should just practice more and learn more of the basic things that can go wrong. Thanks for the tips!

Doesn't really matter. You can try learning one or multiple. You will still constantly be faced with opponents who deviate. Also, openings just help you get pieces out with a certain theory, etc. but they don't guarantee any kind of advantage even, your opponent has to screw up for that. 

If you want to beat your opponents consistently, just take the free pieces they give you. At this level both of you are still giving each other pieces for free. Reduce the number of times you do that by checking to see if your pieces are under attack and if they are defended enough, and if they are lacking, fix it. Also check for if your opponent has given away their pieces for free, and take them when they do. This alone will improve your game by a lot.

If you want examples, I can probably check through some of your games and pull them out. But I have regularly found this to be the #1 thing to fix at these ratings. 

You can start with 1.e4 and try to learn those openings first that your opponent's are playing against you most often. Focus more on understanding rather than memorizing.

thanks guys will try that

Yes you can test yourself how strong your ability in chess