Go to the Home page, look under the Hosting Resources menu block and click Qmail Admin.

Fill in the User Account, Domain, and Password. If you are the Postmaster for the domain, leave the User Account as Postmaster.

For normal users - you can modify your password, name, and/or forward your email to your yahoo account, for instance.

For Postmasters - you can manage all mail accounts, aliases, forwards, mailing lists, and autoresponders.