Procedure:
Log into cPanel on the account to add the domain on.
Click "Domains" under the "Domains" section.
Click the "Create A New Domain" Button.
Enter the domain name to add in the "Domain" text box.
Deselect the "Share document root (/home/username/public_html) with "domain.tld"." option.
Enter the deirectory where you want the files for this domain to exist.
Click the "Submit" button.