How could i have won?

somehow, i inserted my game as a puzzle, sorry. i thought i played decent until the endgame, what plan should i have had going into the endgame?  If you click on move list, you can go through the game normally.  After move 32, is where i lost the endgame.

After 32 ...cxb6 the endgame is not clearly won. The doubled pawns on the b-file mean black cannot easily exploit his pawn advantage. Maybe Rc6 preparing Qb6 would have been better

You had a great position coming out of the opening, but I probably would not have played 16...Re8. Some options include:

16...Bxe3 17. fxe3 (Qxe3 Qxe3 18. fxe3 Bxc2 nets a pawn for Black) Qg3+ forces White to give up castling (eg. 18. Kf1 Rhe8, when Black has a nice attack)

16...Nd4 (Probably what I would play) This move postpones White castling by attacking c2, which is annoying for White to defend. If 17. Bd3, then 17... Bxd3 18. cxd3 Nb3 forks White's queen and rook, while if 17. Bd1, then Nf5 forces White to postpone castling once again, since 18. 0-0 is met by 18... Nxe3 19. fxe3 Bxe3+, winning White's queen.