Wow ... you're either brave or a geek! I have to assume that since you're here, you're comfortable enough to fiddle around with your registrar's settings. What you need to do from outside Radke Land is fairly limited, so let's get started.
When you register your domain name, make sure to provide either valid contact information to the registrar, or use a proxy contact service (and provide them with valid contact information!) Your registrar will likely start using your address right away for their own advertising (this is a 'service' they provide, called parking your domain).
Your next big decision is to decide who should provide your DNS (Domian Name Service). Radke Land provides this service, and it's really not a whole lot of trouble to set up, so feel free to ask me. Whether Radke Land provides your DNS, or someone else does, you still need to know what information goes into your DNS. If you went with the previous example, you may want the following DNS entries:
You also want to think about what happens if someone goes to gobblygookly.imsupercool.com. If you want every subdomain to go to one of your other designated domains, you'll probably want to use a wildcard (*.imsupercool.com). In the list above, are you really going to setup your own mailserver? If you want Radke Land to manage your email, omit the mail.imsupercool.com entry, and set your MX Record to mail.radkeland.org.
If you want Radke Land to manage your DNS, set your name servers to:
ns0.radkeland.org
ns1.everydns.net
ns2.everydns.net
ns3.everydns.net
ns4.everydns.net
And make sure to tell me who's hosting your email, website, and others.
As always, I realize this help page may be a bit messy, please leave comments or requests for clarifications.