If you're adding a domain that wasn't registered with FunnelVitality.com, you will want to be sure that your DNS is pointing to FunnelVitality.com.
Sometimes DNS can take up to 48 hours to propagate.
Then log into cPanel and click on 'Domains'.
Enter the domain name you want to add in the "New Domain Name" field.
You may want to uncheck 'Share document root' if you want to keep your websites in separate folders.
Click "Add Domain" to complete the process.