Fill in your name, your email address, a reply-to address (if different), organization, and location of a signature file (if you use one).
Next, click on "Mail Servers" subcategory, "Add", and fill in the server name that your domain host told you to use (Netscape does IMAP as well as POP3). Your "User Name" must include the "@mycrib.com" (substitue your own information, of course…). Click on "Remember password" if you want to, and after the first time you won't need to put it in again. Check the other boxes as desired. The "POP" (or "IMAP") tabs have additional personal preference selections. Click "OK," and you'll be returned to the "Mail Servers" screen.
For the outgoing, use your ISP's SMTP server if you can; your mail will go out faster. Otherwise, use the server your domain host gave you. If you use your domain host, and they require authentication, fill in the username (including the "@mycrib.com").