At first, make sure that your plan allows you to add Add-on domains and that they are not been already added.
To add an Add-on domain:
- Log into cPanel using steps given in https://secure.lightningbase.com/index.php/knowledgebase/6/How-to-Access-cPanel.html
- Click "Domains" under the "Domains" section.
- Click the "Create A New Domain" button.
- Enter the domain name to add in the "Domain" text box.
- Deselect the "Share document root (/home/username/public_html) with “domain.tld”." option.
- Enter the directory where you want the files for this domain to exist.
- Click the "Submit" button.
