setting gateway IP from command line

[abramo@speakeasy.net]

I'm sure this is a very basic question but I have zero experience with debian.  I work at a computer shop and we installed debian on a pair of new machines for a customer.  He needs to assign an IP and gateway to one of them and could not figure out how to do it so he brought the machines back to us and begged.  We are basically a windows only house.  I'm the only linux user and all of my experience is with mandrake and slackware.  I've always used X in both and there is no X on this machine.

I just need the command name and I can do it from there.

Thanks all!


Abe
Jesus saves, 
Allah forgives,
Chuthulu thinks you'd make a nice sandwich.