adding a oem sub to a mach oem stereo

[turbochardged]

I did find out I have a premium dual audio radio with rear controls and 6 disc cd changer but no sub. I want to add a oem sub and speaker to it. Yet I just found out I have no sub wiring harness. I bought the amp, box, and harness from a junk yard.
I wired it all in but no sound (it work when i did a bench test), but a head phone icon appeared on the headunit. The head unit model is f87f-18c868-cd.