I just got a VPS with Dreamhost. I was trying to login as root via SSH, but I don't have the password. I don't believe I was ever given the root password. How do I change it?
You don't. What you can do is create an Admin User in the Panel; this user will be given privileges to use the "sudo" command to run commands as root. (This is a much more secure setup than logging in directly as root.)