Addon domains are additional domains on your account that act as their own site.
The files for these Addon's go into the folder which will be made when you make the addon.

The first step would be to e-mail support requesting an addon domain.
After you receive the details you would then log into your cpanel and click "Manage Addon Domains"



Next you would fill out this form:



Make show to replace AddOnDomain.com with the actual domain you are adding.
Also make sure to replace the UserName/SubDomain Name field with what you would like it to be as well as the Password field (Please make sure to have a secure password).

After this press the add button. You should then see a page on how to log into the addon domain via ftp. It should look like the following:

AddOnDomain.com has been setup. It can be accessed via the subdomain AddOnDomain.YourDomain.com . Ftp access has been granted with the username AddOnDomain and the password PassWord .

To log into FTP you would use these settings:

Host: YourDomain.com
Username: AddOnDomain@YourDomain.com
Password: PassWord

You will also need to change the nameservers on all Addon domains.
Please e-mail support if you need the nameservers.