Huh? You don't need the terminal. You can chose the environment in the login screen, there's a drop down menu besides your name. Not exactly intuitive, but very easy to find out using Google or a forum. If you want Gnome 3, you can install it from the repositories (again, no terminal required, at least not in 11.10), and it'll be there in the drop down menu.

Zero understanding of *nix required here.