Once you are logged into your cPanel account:
Select "Addon Domain" under the "Domains" section:
Once you are finished filling in the details, select the "Add Domain" button.
Next, you will need to fill out the details of the add-on domain:
- "New Domain Name:" You will put in the domain.com without put www in the name!
- "Subdomain:" This will be use for addon/subdomain FTP account username.
- "Document Root:" This will be the folder cPanel creates in your main FTP accounts.
- "Password:" fill in any password you want here.