Go to the hosting section of your account. Click on the server you wish to configure, and then on Web Server

The first information you need to provide is an e-mail address. This is the address of the person in charge of the HTTP server. It will, for instance, be displayed on the server's error pages, should users want to notify this person.

The HTTP server needs to know the name(s) of the domain(s) (web sites) it will be hosting. This includes all of the related sub-domains (www.example.net ; subdomain.example.net…).

Each virtualhost needs to have a user selected. This will allow you to share the management of each of them with a specific user. Of course, the user "admin" will always have access to all virtualhosts in the server.