I've looked at a few of your games, and the biggest problem seems to be that you just give away pieces with no reason at all. In one (played at 3 days per move), you took a bishop with your queen and allowed a recapture with a pawn.
In order to improve, you would do well (as someone else recommended) to get "The Complete Idiot's Guide to Chess" and study it from cover to cover. Then get on here (or chesstempo.com) and do tactical puzzles until they're coming out your ears. Finally, use the resources here to study (or at least play over) some of the games of the great masters and see how they develop. I'd start with Morphy--one of the greatest players whose play is also very accessible.
Good luck.
k