Before adding an Addon Domain name you need to point your addon domain name server to your main domain name server and you will need to wait for domain propagation. It usually takes between 12 and 24 hours.

1. Log into cPanel on the account to add the domain on.
2. Click "Domains" under the "Domains" section.
3. Click the "Create A New Domain" button.
4. Enter the domain name to add in the "Domain" text box.
5. Deselect the "Share document root (/home/username/public_html) with “domain.tld”." option.
6. Enter the directory where you want the files for this domain to exist.
7. Click the "Submit" button.

If the domain is successfully added, you will receive a message like this.