To access Cpanel you must first configure it through WHM.
To do that navigate to the following link http://your-ip-address:2086/
The username will be "root" and the password will be the one you have specified.
Once you have logged in to WHM follow the basic setup steps and create a new account.
Once completed, access Cpanel at http://your-ip-address:2082/ and login with the account details you have just created.