can't shut down

[Douglas Pollard]

I'm a newby to debian linux and feeling pretty dumb. I have managed to partition my hard drive and install Debian but I can't figure out how to get into root in order to shut down my machine. If I am in Gnome how do I close Debian-linux down. If someone would walk me through from Gnome I would be thankful. At the present time I am shuting down with th off button on the front of my machine.                                                 Doug