I bought http://www.zroenergy.net at http://www.godaddy.com so I know how it works first hand.
First go to http://www.godaddy.com
Then go to My Account, and login.
Then go to Manage Domains under the Domain section of the page you get after logging in.
Now the domain you bought will be listed. If there is a lock next to it, click on your domain name. On the right of the next page under "Domain Details" click unlock domain.
After your domain is successfully unlocked. Click on the domain again to bring up the "Domain Details."
Then under "Nameservers Summary" set the nameservers to
NS1.TRAP17.COM
NS2.TRAP17.COM
Now lock your domain and log out of http://www.godaddy.com
Now login to the Control Panel of your site. Found at http://username.trap17.com/cpanel
Under "Site Management Tools" Click on "Parked Domains."
Add the domain name you bought from http://www.godaddy.com to your list of domain names. If you did it right, your domain will appear under "Current Parked Domains."
You're finished! However it will take some amount of time for the domain to propogate before it appears on your computer. It may take 30 minutes or up to 2 days for it to appear, which depends on your ISP's cache.

