Total Noob Here

Ok, so, I’ve had my domain forever, and finally decided to do something with it, so I’ve signed up, I’ve installed all the one-click stuff, switched my nameservers with my domain registrar, but everytime I try to access my blog or forums or whatever, I just get the default godaddy page instead. How do I access my stuff so that I can start adding content?

You can manage your files via DH panel --> Domains --> Manage Domains --> WebFTP. Please note that it takes a while for the new domain to propagate.
http://wiki.dreamhost.com/Building_A_Website

How do you get to the DH panel?

Easy: https://panel.dreamhost.com/