Need a bit of help with my Mail account...

Well, when I first got my Mac, I decided I would try the free 30 day trial of .Mac. During this time, I made a Mail account. Unfortuantly, I forgot to write down the password. After, oh, maybe 3 weeks, I realized that in order to get mail, I needed to sign in. I enter my account name and what I think would be my password. Well, it rejects it. After trying many other different passwords for around 30 minutes, it still is rejecting my password. Is tere a way to make a new password, maybe? Can I make another account? Thanks in advance.

 

So I made a new account. I thought my problems were over. But they aren't. Whenever it asks me to input a password, it says it rejected the password from my old account. How do I switch to my new account?