Most web hosting plans allow for multiple domains to be hosted under the same hosting accounts. However, you may have had trouble finding out how to add a domain to your hosting account.
To add a new domain to your web hosting account, simply use the domain manager in your web hosting control panel. Within the domain manager, you will be able to select from a variety of preferences and options that will let you associate your new domain with the hosting account. Most control panels differ in their options, so you may need to view a tutorial for your control panel.