I lost... What could i have done better?

Lol your rating is that high and you haven't heard of the dutch? It's a viable opening, though it's not ideal no.

The dutch is the favourite of J.polgar

I agree that 9...h6 is a bit too panicky. Let's say you ignore him, what will he do? 10.h6 g6 doesn't look that dangerous yet.

Anyway, your whole plan (the Dutch, the bishop on b7 etc) was to control the white squares in the center. Couldn't you have played 8...Ne4 to make use of those squares? Otherwise, 8...d6 to develop the other knight to d7 looks reasonable. I don't get 8...a6.

After his 12.0-0-0 you should have attacked on the queenside.  I'd be looking at moves like 12...c5!? or 13...c5!?, ...Nc6 blocks your c-pawn and that meant you didn't really have a pawn lever to work with.

After 22...g5 I think it's just dead lost.

According to Shredder, g5 is where you really lost control of the game.  Always think twice about pushing pawns in front of your king with no pieces to defend it! 

+2.61 at that point, and it's hard to come back from such a blow.  I think the openign was decent, and you have a good grip on things.  :)

Yeah I believe you should've played ne4 sooner...like instead of playing a6, then if he still castled qeenside you could counterattack on the queenside with moves like c5 like scarblac said, instead you played the passive h6 move and then when he was trying to create weaknesses on yourkingside you just helped him with the h6 move.  It seems you are lacking a plan, and just making moves that arent acting as a whole to better your position, your oppoenent had a plan and that was to obviously attack on your kingside with a pawn ambush which you probably could've delt with if u just didnt make a couple silly mistakes, but all in all thats what im feeling.

You can also try Computer Analysis for any of your games on this site.  As a new basic member you can have one game per week analyzed.

You can access this feature by viewing the recient game that you want to analize then select Computer Analysis above the message block to the right of the game board.

I hope this helps.