If I am in the command line interface how do I start running a GUI like KDE or GNOME?

And any advice on how to get the GUI to fill up the screen on my laptop (Toshiba Sattelite 5005-S507, NVidia GeForce 4 440 To Go, Mandrake 10.0)

I tried the help on the wbsite but being new at this It's a bit complicated, I need serious Barney Style.
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D, world destruction
Over and overture
N, do I need
Apostrophe T, need this torture?-They Might Be Giants