4 Steps:
1. You need to add your domain name to your computer as a host. You do this using NetInfo Manager which is in Applications -> Utilities. Kilowatt wrote an excellent
How-To on how to do this step.
2. You need to tell Network Solutions that your Mac is a host. For this, all you have to do is send them an email saying something like, "I've registered whatever.com and I would like xxx.xxx.xxx.x (your IP address) registered as a host so I can register that domain". They'll do this in a couple of days, no fee.
3. You've registered your domain, but you need to tell it to use your Mac as a DNS server. For this step you have to go back to the place where you registered your domain and enter your computer's IP address as the primary DNS server. Your IP address is in System Preferences -> Network. You best have a static IP, or you'd be better off using a service that points your domain to your machine for you.
4. You'll need to add your new domain name to Apache. Edit the httpd.conf file in /etc/httpd/ look for the line:
#ServerName smallsoldiers
and change it to:
ServerName
www.superfundomain.com
Save and restart Apache.
Final word: If you'd prefer, you can add the new domain in as a VirtualHost like this in httpd.conf:
<VirtualHost>
DocumentRoot /Users/username/Sites
ServerName
www.superfundomain.com
ServerAlias superfundomain.com *.superfundomain.com
</VirtualHost>
There are other configuration options available too.
I hope this helps!