This tutorial explains how to create an email account for one of your domain names. Go to your Site Tools > Email > Accounts:

Next, you will need to type in the new Email account you want to create and fill the necessary information for it.

Here are the fields you need to fill in, in order to create your new account:

Once you’re ready, press Create at the bottom. That’s it, in a few seconds, your new email account will be created.