21...Bd5 and Black would have just been up a piece for nothing. If Black doesn't simply drop the e6 pawn there is zero White activity. Nothing after this point needs discussion.
You did not play the opening moves very well. It looked like you were bringing pieces out just to bring them out, without an idea of how you were going to attack Black's Hippo setup. 5.Bc4 makes no sense with a Black pawn already on e6. When you later played e4-e5, he was able to play ..d5 closing the position and gaining a tempo. d3 was probably the correct square for this piece. 7.O-O is obviously a good candidate but maybe something like 7.d5!? better meets the needs of this position !?? 8.Re1 was another questionable move strategically, it seems you want to have this rook on f1 and play f4-f5. You are not guaranteed to be able to open the e file, but with pawns on e6 and g6 you should be able to open your f file. 10.Bb3 doesn't seem like the bishop has much of a future on this diagonal, 10.Bf1 was an alternative, but already I don't like your position. I would have been playing to expand on the queenside with ..a6 and ..c5 instead of what your opponent did. 10...Nf5 was decent, but 11...Nh4 is mysterious in that position (only after g4 is this move necessary). Better would have been 11...h5! establishing a grip on the kingside.
I was pretty lost in this game but my opponent made a couple of mistakes and yea i managed to win it some how, please tell me what could have i done better and where were his mistakes exactly.
The ratings are chesscube ratings and i know that they are way inflated but i think i am between 1350-1400 in standard and blitz.