03 gti turbo air/fuel

hey ppl i was wondering if sum1 could give me some input on hooking up a air/fuel ratio guage on my friends 03 gti turbo..for instence how many wires is the o2 sensor and wheres it located and what colored wire would i hook the guage up too. the gauge been installed forever but not hooked up and i thought id help him out with it..i didnt look under the hood and im not educated on vw's so any lil bit of input will be appreciated. thanks:smokin:

bump