To be sure, go to www.whois.net, enter your domain name there. Under "Registrant Contact:" or "Created by Registrar:" you will find who is the registrar for your domain name.
There is also a section called "Name Servers:" that display your actual nameservers.
Whatever the registrar is, you will have to change your nameserver when you change your host (This apply to any host). If it's creativedata (I doubt but possible) log in to your actual account there, go on your domain informations, and edit the Name Server for Dreamhost. It should work perfectly.
Dreamhost will communicate the Nameservers informations as soon as you have your website host with them.
Also if you still can't do this just tell us what's the domain name? Will tell you the data you need to know.
As Lensman said, What do you mean by "the guy that maintains the website?" the webdesigner?
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