If you want to create an Add- on domain in your cPanel then you have to follow the following points :
1. You have to log into your cPanel.
2. Select the “Add-on Domains” option.
3. After select “Add-on Domains”, you can see the following page.
4. Enter the new domain which you want to point.
5. Enter the username/ directory name.
6. Create a password for the Add-on domain. It should be 6 to 8 characters
7. Select “Add” button which is present below.
8. At this stage, you would have successfully created an add-on domain. The FTP access is automatically setup by cPanel. Now you should upload your files to yoursite.com/add-on, because cPanel automatically creates sub folders in the root(public_html)directory for the newly created add-on domain.