1. Log into your cPanel account.
2. In the "Domains" section, click on the "Addon Domains" icon.
3. Under "Create an Addon Domain" you should enter your addon domain name.
New Domain Name: your addon domain name like example2.com
Subdomain: it will be automatically filled in by cPanel.
Document Root: it will be automatically filled in by cPanel.
4. Click on the "Add Domain" button.
If the domain is successfully added, you will see a message like this