Basic WHM setup and DNS problem

I assume you own a domain. Let's call this domain: example.com.

Your servers hostname should be something.example.com, substituting "something" with a string of characters that makes a valid hostname. This can be something like server1.example.com or cpanel-server.example.com. You would also substitute example.com with your own domain.

For nameservers, most people call their first nameserver ns1.example.com and their second nameserver ns2.example.com. This naming convention is not required, but it helps avoid confusion between what is the server's hostname and what is a nameserver.

Lastly, you would go to your domain registrar where example.com is registered and do what's known as "gluing" or "setting up glue records." Basically, all you are doing is telling the rest of the internet at what IP address(es) to find your nameservers. From a technical standpoint, both nameservers can run on the same IP address, but some domain registrars do not allow this practice. Your domain registrar will need to help you with the gluing as there is no standard way to do this among all domain registrars.

Now, after going through WHM's Getting Started Wizard, you can start creating hosting accounts by going to "Create a new account" under the Account Functions section in WHM. Those domains would just need to set their nameservers to be the nameservers you created earlier (e.g. ns1.example.com, ns2.example.com) so that web browsers know to find that website on your server.

Regarding access to WHM, you can use any IP address, hostname or domain on your server to access WHM. Access to cPanel and WHM is determined by the username and password provided, not which URL is used to access the interface.