Analyse my game plz

 I am not an excellent chess player. In this game I lost ,but I won't hesitate to post it. Please analyse my game. Thanks!        

Thanks.

Look at the position you were in after 9...c6 below:

The first thing you notice is the Queen's side. You have little to no influence there because of the pawn chain. Your light-squared bishop is also tied up. You could have avoided this by taking back the c4 pawn in the opening (see below). Sorry i haven't been able to offer much because i'm pushed for time this morning.

3. cxd5 is best, as your opponent has not protected his pawn with another pawn.  It gives you more central control, and you can gain a tempo with Nc3 when the queen recaptures

19. Nxa4 creates doubled isolated pawns which are weak and the front one cannot be defended from behind by rooks

Yes, 2...g6 was lame and begged you to play cxd5 and e4 soon thereafter. All your other problems would have been avoided with this early take.

Just a few thoughts...

As already mentioned, after 1.d4 d5 2.c4 g6 it would have been better to continue 3.cxd5...4.Nc3...5.e4...Once your opponent plays g6 you're completely out of the main line so it's time to play aggressively and use the advantages of whatever opening you have chosen.  Playing aggressively in this case in the Queen's gambit is to use your c pawn to wipe out one of his central pawns to give you better control of the center.

On 3...dxc4, again you should have been aggressive with your e-pawn and pushed it to e4 right away, taking the center he so generously gave away. You ended up moving it there at move 9 anyway so this would have saved you a move.

After 4...Be6 you should have moved 5.Bxc4.  This would have gotten back your pawn and developed one of your kingside pieces and is much more aggressive than Be2.  If he had taken the Bishop with his, Qa4+ (which is a very common move in Queen's gambit openings if your opponent is not careful) would have taken it back.

a6 is a very common preparatory move in QGA situations because your opponent is preparing for b5 which protects his c4 pawn.  a4 would have been the correct answer here, but you didn't seem to mind letting him have the cpawn.

Starting at move 11 you become overly concerned with the ensuing attack on h7, but you really had no need for concern.  That plan would take awhile to unfold and meanwhile you had other more important concerns.  Like how to counterattack.  One idea would have been to bust open the Queen side where his pawns are totally cramping your style. a4 would have been a good start to that.  Your idea of taking control of the d file was good as well, but you didn't do anything with it. You should have pushed with your d pawn to make some things happen.  However, even after that you still must deal with the Queen side space issue because your light bishop was useless to you the entire game.

I'm going to skip a few moves because they are mainly reactionary to his attempt at h7.  Your move back to Ra1 I think turned out good for you because it seemed to distract him from his plan.  He thought you were going to counterattack, i think, which is why he moved his Knight that way.  After Na5, you should have taken with your Knight.  It would have given him four doubled pawns and opened up that whole side.

21...Rf7 was simply to double up his rooks and push his f pawn.  This is your last chance in the game really to make something happen, but again you are too worried about what he is doing.  His Queen side is completely vulnerable to attack.  Both of your rooks are there, and most of his pieces are on the kingside.

If I could say one more thing, while it's good to try to figure out what your opponent is planning and react to it, you will not win a lot of games playing purely reactionary moves, which is basically what you did.  Often the best defense is a good offense.

5. Bxc4 would lose, as Qa4 is met with b5