To use multiple domains in the same account, the domain must be configured in the cPanel control panel. There are two methods for adding multiple domains: "Parked" and "Add-on".
Parked Domains show the same website as your main domain, and Add-on Domains can display an entirely different website, and include an FTP account that you can use to manage the content for the Add-on domain. This can be useful when you wish to delegate responsibility for managing the content to another party without providing access to the entire account.
For Parked Domains, go to Domains -> Parked Domains in the control panel, and add the domain(s) you wish to display the same content as the main domain.
For Add-on Domains, go to Domains -> Add-on Domains in the control panel, and add the additional domain(s) you wish to display a different website under.
For each one of the Add-on domains, you will be prompted to create a folder that is associated with the domain name, where you will upload the website files. The new folders will be created within the main site folder.
You can also create a specific FTP account for each domain. This account will have access only to the folder defined as the Add-on domain folder, and its subfolders.
Once the folder has been created, you can upload your website or application into the designated folder, or use the Fantastico web application installer to automatically install and set up your chosen application for the Add-on domain, by selecting it from the drop-down box during installation.