If you have either a Multi Domain, Professional or Business packge then you have the facility to host more than one website on your hosting space. To do this, follow these steps:

1) Order the domain name (you can do this directly at nativespace.com)
2) Change the nameservers for the domain name to point to the nativespace server that hosts your space.
3) Login to cPanel
4) Click 'Addon Domains'
5) Enter the necessary information (username/password/domain name WITHOUT the 'www') for the new site.

A subdirectory will be created in your main space named the same as your username (see point d above) and this is the root for all the files for your new site.