To add an addon domain, we can use the Addon Domains feature in the Domains section of the cPanel interface.
- Login To Cpanel
- Click Addon Domains from the Domains section.
3. Enter the domain name you want to add; no "www" is required before the domain.
4. The Subdomain and Document Root fields will be generated automatically. The auto generated default values are recommended. 
5. (Optional - skip to step 6 if you do not require an FTP account.) Simply check the box next to the option to create an FTP account associated with the addon domain.
6. Enter a username that you'll remember as being associated with this domain later.
7. Give the FTP account a strong password.
8. Click Add Domain.