I already have a domain name, how do I use that?
If you already have a domain name, or want to register one yourself externally, it's still very easy to have just your hosting with us.
Most registrars will have a place where you can manage the DNS for your domain. I say most because I'm sure there are some shady ones out there that don't let you for some reason, but all the major players should have it pretty easily accessible.
Since there are dozens or more registrars out there, I won't go into absolute specifics like 'click here, tpye this, click that', but I'll make it as easy to follow as I can.
On your DNS or Domain Name Server screen on your registrar, there will be a place to enter custom name servers to use instead of their default ones. For GoDaddy you'll see something like 'NS1.SECURESERVER.NET' as an example. Select the button to enter your own, and set them to the following name servers:
ns1.fhhost.net ns2.fhhost.net ns3.fhhost.net
And that's it! Once the name servers are set, after they propogate through the great series of tubes we call the internet, you will be able to start working on your site with our hosting. For the more advanced users, you can manage your DNS records in the Plesk panel, under the DNS option in there. From there you can set your records to anything you like.