To create an email address:

Go to Mail.
Click Create Email Address.
Type the left part of the email address before the @ sign, and, if you have several domain names on your account, select the domain name under which the email address will be created.
Leave the Mailbox checkbox selected. Clearing this checkbox makes sense only if you want to use this address as a mail forwarder, which will forward all incoming mail to another address.
Specify the mailbox size or use the default size defined by the providerís policy or your service plan.
Specify a password consisting of five or more Latin characters.
Click OK.