Here is an article that outlines how to setup a new mail account in the Mac Mail application named Configuring Mail for your email account found here: http://support.apple.com/kb/ht1277.
I recommend this part of the article:
- Open Mail.
- Choose Add Account from the File menu. If this is the first time you've opened Mail, you will be automatically prompted to add an account.
- Enter your Full Name, email address, and password. See Mac 101: Mail article for more information.
If you need to setup the mail account settings manually, the information for that is farther down the page.
All the best,