How do I fix it so that my site comes up for my domain name, not just my IP address?

All you need to do is go to your registrar and point your domain at the following nameservers

ns.rackspace.com
ns2.rackspace.com

Also, if you didn't know what domain you wanted when you signed up, make sure to go to the MC support page and fill out a domain name change form.

If you are not sure who your domain registrar is then you can go to BetterWhoIs Lookup and it will tell you who your registrar is and what DNS (Domain name servers) that you are using.

To change the DNS settings then you will need to login to your domain manager (called different things at different registrars) and you will either see a tab for "DNS Settings" or just one for settings with DNS listed underneath.

NS.RACKSPACE.COM will be the Primary
NS2.RACKSPACE.COM will be the Secondary

Now it is going to take anywhere from 24-72 hours for the domain name to switch over to the MonsterCommerce servers, so just keep checking on it to see where it is at.

Of course if you have any problems you can always call the guys at MC tech support, they are great at walking you through things like this.

EComGal

Nice link EcomGal.

I would also like to recommend OneWhoIs.com

OneWhois.com automatically queries the correct ICANN registrar for all .com, .net, .org and .edu domains.

It is a low bandwidth site: No annoying banner ads or other bandwidth hogging graphics. Just the information you are looking for about a domain name. It also uses SSL encryption for all communications between your web browser and OneWhois.com for added protection.