Did you not unerstand in your other thread that you have a MKIII and your in the completely wrong forum. Although radio wiring is fairly similiar and simple.
with a quick google search i found this wiring diagram for you
http://faculty.ccp.edu/faculty/dreed/campingart/jettatech/audio/baseradio.jpg
if i understand correctly, you cant find your RED/BRWN Switched 12v power source.
1st Make sure you look real good on your wiring harness for it. Peel away some of the wire wrap and see if it isnt tucked away. if it impossible to find then
2nd find a switched 12v power source. Now i know in mkII's people use the Defrost Power wire for this. Im guessing that it is the same for a mkIII. Once again, try the test light with this. if this doesnt work try
3rd wire in a switch. Get a length of cable. Nothing huge, but not to thin. I used a 18 gauge audio wire. If your head unit does not have a Fuse, Wire one in. 10-15 AMP will work just fine. Simply connect the wire to the battery, run it inside the car to the Mounted switch (wherever suits you best), and then to the fuse, and finally the Head Unit.
It shouldnt take you more than 1 hour to do, and if none of these tips helped you, feel free to post in the MKIII (3) section of this forum for more help.
