To configure your mail program, you must first setup your email accounts. This can be done through your cpanel. For information on how to do this, you can watch the flash tutorial on it here:
http://charlottezweb.com/tutorials.php
Once that's configured, go into your mail program and configure your settings using the following example:
username: your full email account (i.e. jason@charlottezweb.com)
password: what you created
pop server: mail.yourdomain.com
smtp server: mail.yourdomain.com
That should be it!
If you are using Earthlink and certain other ISP's, it may be necessary to use their smtp servers in order to send outgoing mail. This is ISP specific.
Jason