Trying to interface a matrix keypad to arduino

Hi everyone,
I've got a problem, I need to interface a 12-key matrix keypad to the arduino. I know the vb software side of it, but don't know where to go on the arduino software side of things. the application is for a alarm system.
all help appreciated,
uberdum05

This looks like what you are after:-
http://www.arduino.cc/playground/Main/KeypadTutorial