puzzles up to 2100 but how do I use this in a game?

The solution is to stay awake and pay attention to the game. There are no tactical opportunities at every move, but there are plenty.

Let's look at a random game of yours:

https://www.chess.com/analysis/game/live/23725715069

Your opponent plays 12. - Nc6??, hanging the knight (it's attacked by your queen and it's not protected. This would be a 200-rated puzzle. In the game, you made some random legal move and you let the opportunity pass.

Same game, later: you played 16. Nh4??, hanging your knight for no reason whatsoever.

Good question. I think the problem is that doing puzzles is not the only thing there is to study about tactics. Studying tactics has 3 aspects: 1. learning about the tactics themselves; 2. learning pattern recognition and improving vision by doing puzzles; 3. learning how to spot tactics. Your question falls under the last category. 

So, how do you spot tactics? There is more than 1 technique that you could use. One of them is the 'check, take, attack' method. Tactics can have 3 targets: a square, a piece (or pawn) and the king. Basically we can put them in check, we can attack an undefended or insufficiently defended piece or we can threaten checkmate. When you get stronger it might also be a strategical threat, but checkmate is far more common, so we'll simplify. The method of check, take, attack works like this: every move you look for all the moves that put your opponent in check, that take a piece / pawn of theirs and/or that threaten checkmate. Looking for all these moves will help you find tactics. For example:
- when you see 1 move that is both threatening checkmate and attacking an undefended piece, you've just found a double attack
- when you can see that you can take their bishop with your rook, and their knight with your bishop, you should be able to work out that you can do an eliminating the defender tactic if one of them is only defended by the other. 
etc. 

At the beginning it's all very overwhelming. It will take time to look for all these moves at first. It will cost you a lot of time on your clock. Later on it will become second nature. Looking for tactics first, and then picking your 3 candidate moves from which you'll decide one to play is a decent way to give yourself some structure when thinking about a move, even though, later on, it will be a much more intuitive process.

Being good at tactics and being able to spot/create them in games are 2 different things. 

Use a site/book/etc. that allows you to play through the entire game.  That way you can see how the game develops, how the weakness was created, how the winning side took advantage of it.  Learn what the motif was.

Puzzles will also help train you to select the best move option and the correct order of moves, I.e. stronger puzzles will have your King under threat of mate, an unprotected minor piece to capture, a favorable exchange and a 3-move mate.  All viable options, but most will not look for the “win”.

Like RAU4ever’s idea on tactics; would recommend the acronym “CAT” so its easy to remember.  Would also add an “s” for Safety (your king & your pieces).  If you go thru this process with every move, whether playing a person or computer, you will get better and enjoy the game more.

Great comments; all the best. 

Dear Djweeksy,

I am a certified, full-time chess coach, so I hope I can help you. Everybody is different, so that's why there isn't only one general way to learn. Solving puzzles (improving your tactical skills) is just one of the main areas (I'll talk about it later), so even if you have good tactical skills it doesn't mean that you can find the best moves in a strategic positions. First of all, you have to discover your biggest weaknesses in the game and start working on them. The most effective way for that is analysing your own games. Of course, if you are a beginner, you can't do it efficiently because you don't know too much about the game yet. There is a built-in engine on chess.com which can show you if a move is good or bad but the only problem that it can't explain you the plans, ideas behind the moves, so you won't know why is it so good or bad.

You can learn from books or Youtube channels as well, and maybe you can find a lot of useful information there but these sources are mostly general things and not personalized at all. That's why you need a good coach sooner or later if you really want to be better at chess. A good coach can help you with identifying your biggest weaknesses and explain everything, so you can leave your mistakes behind you. Of course, you won't apply everything immediately, this is a learning process (like learning languages), but if you are persistent and enthusiastic, you will achieve your goals.

So, the question you asked is not so easy to answer, but I can tell you one thing for sure. In my opinion, chess has 4 main territories (openings, strategies, tactics/combinations and endgames). If you want to improve efficiently, you should improve all of these skills almost at the same time. That's what my training program is based on. My students really like it because the lessons are not boring (because we talk about more than one areas within one lesson) and they feel the improvement on the longer run. Of course, there are always ups and downs but this is completely normal in everyone's career.

I hope this is helpful for you.   Good luck for your chess games!