beginner!

I've just played my first chess match against the computer on the easiest setting and lost badly!!!What should be my next step in learning this great game?

Playing games is the best way to learn when you're starting out.  Lots and lots of games.  During and after games think about how to improve your thinking or try different plans.  One good tip is every time your opponent moves, look to see what it threatens.  At first you'll only do this part or most of the time, but when you can pay attention to your opponent's last move every time, you'll be a lot stronger.  If you only check 19 out of 20 times you can drop pieces for nothing at least twice a game, which is a sure way to lose as you start playing tougher opponents.

You should know the opening is about 1) speed of development (get your pieces off the back rank and castle) and 2) control of the center (the 4 center squares, occupy one of them with a pawn and in general maintain a pawn there).  And you should know the basic tactical motifs "forks" "pins" and "skewers"  in terms of study, you can't go wrong with solving tactical puzzles.  You have to study all aspects of the game to get really good, but tactics are very very important until you're pretty much a master at which point maybe you can put them at #2

For a lower level player its all about improving tactics.  By tactics, I mean seeing threats, and being able to calculate combinations of moves at least a few ply deep.  You need to be able to see where the opponent is threatening you, and where you can threaten the opponent.  Like Orange Honda said, if you want to put in study time beyond game time, solve tactical puzzles.  You can do that on chess.com with the tactics trainer, although you are limited to 3 a day if you are not a paying member.  Another good site with tactical puzzles is chesstempo.com.  The great majority of the time lower level players (of which I am one) win and lose their games on tactics, rather than some subtle strategic point.  That will come later.

If you want a good introductory book for the novice, I think Yasser Seirawan's "Play Winning Chess" is a good start, and something you could likely find at a library if you can't go out and buy it.  There are more books in the series if you find it usefull.  They are perhaps not the deepest study out there, but they are very novice friendly.

One thing NOT to do: Dont get hung up on opening theory.  There are large numbers of named systems for starting a chess game.  New players sometimes try to put in large amounts of time trying to memorize them.  This is really something for much later in your career.  As a novice the things you need to know about the opening are:  Fight for control of the center of the board, get your peices into action quickly (this is called development), as a general rule develop bishops and knights before trying to bring your queen and rooks into the game, and get your king to safty, usually by castling.  If you can do that, and think about tactics at the same time, you are doing well.

And play alot of games.  Expect to loose alot, but you learn more from a loss than from a win.

Best of Luck!