It should be nothing more complicated than updating the DNS to point to the 3 DreamHost nameservers (ns1.dreamhost.com, ns2.dreamhost.com, ns3.dreamhost.com). If you are talking about a separate domain from the one you registered here, then you will need to add a domain in the Control Panel. You should already have FTP login information (from when you signed up), so you can upload your site stuff to the folder created when you added the domain. If you have a database, you might need to create a subdomain so that you can begin setting it up in advance of propagation.
Simon Jessey | Keystone Websites
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