Xerox Phaser 3330 driver install

Hi Tim,
I downloaded the .deb file to the desktop, then extracted it to there. Then cd Desktop, then bash etc etc. It returns "no such file or directory"
You will note that the instructions from Xerox ask you to type su first, as far as I am aware this is not recognised in Ubuntu I have always used sudo. My limited knowledge of Linux prevents me from knowing if there is a workaround or am I doing something wrong.