Monsoon Stereo Question...help!!

Recently i bought a 2002 grand am GT with the monsoon audio system. I am interested in hooking up an ipod into my car but i do not want to pay for the expensive rip off ipod kits. I looked in the back of my stereo and saw the 12 pin input. I went on the net and found a GM 12 pint auxillary adapter for my car. The only problem i have is i am not sure how to turn the stereo itsself to auxilary mode. I did not purchase or install anything in my car yet, but unless i figure out how to change to auxillary mode or how the hell my ipod will play threw my stereo im not gonna waste my money on the adapter. Does anyone know how the monsoon changes to auxillary mode to play from another source. If so i would appreciate your help. Thanks