How to make a timer?

1

ok, as some of you know, i am making a racing game, it is a time trial kind, but i have no idea how to make a timer without relying on the clock of the computer. I Just want it to count min, sec, and msec. going up. I also need it to stop when it hits the finish line…i am also starting to think this may be a bad idea for a first game. LOL. Well, i will learn from who can help. and please tell me any ways to learn actionscript.