This is a game that I almost won, and then neutralized to win it again!

I wud hv played NxNe6

your fist blunder was 9.a3, you did give away your bishoppair without need. Fritz says you lost 0.6 Pawns there. The second blunder was 14. Rad1 Fritz says e5 is 1.2 Pawns better. You conquer the d-File, get space and/or gain a piece. Move 15 about the same. 22.e6, 23.Ng5, 30. Rxc6 big blunders. 34.Rb8 gives away the knight on c3 but your opponent did not want it. Both players did throw several of their own pieces "in the trash". You need tactic training. Maybe you want to try http://www.snufflenose.com/ats/ its free of charge and improves your weakest tactics first.There are free engines in the net wich can help you to find the errors and better moves. Jose, Arena, Toga, in combination they have an elo of 3000+ and can help to see the weak points of your game.

After the moves 23. you are a piece up. The rules says: If you are better in material exchange Pieces not Pawns. Centralise your knights to exchange one of them. take the open files to exchange rooks, take the 7. rank with both rooks  and win f7 or the queenwingpawns if your opponet dont want to exchange pieces.