Why the hell?

I had a tournament today, and i just don't know what to say. I was great in the opening, i was a lot better in the middle game, and in the end game i just didn't know what to do, and i lost. especially in the last game, i had a rook and my opponet had a knight and connected pased pawns, and i just coudn't stop them anyhow! How can i improve my endgames? I really need help.

Buy "Capablanca's Best Chess Endings" by Chernev.  Silman's Endgame course is also a good book.  

Pandolfini's endgame course is good.  Even some good info on Wikepedia on endgames you need to know what is winable and what is a draw.  From there they can be tricky and endgame play is what seperates alot of good players from average ones.  I lose plenty in the endgame and one thing that has helped me lately is to try and see what the endgame is likely to look like as soon as possible.  Even as early as right after the opening sometimes in certian games I'm already preparing for the endgame with particular pawns or rook placement.  Other then that really it is a matter of practice and having been in the positions before.  Rook pawn and knight endgames can be extraordinarily complex so you will easily run into time trouble otb.  How active is your King in the endgame you want to use the king expecially in the endgame..  In rook endgames don't needlessly check the king but use it to fence in or limit the opponent kings movement.  You want your rook behind your pawns if possible and don't be affraid to use your king as an escourt for the pawns.  Don't feel bad a rook against some connected passers and knight there may be nothing you could of done.  Any way to post the game?