help with ipod adapter (cd changer type)

[jordcoe]

Bought this last week thinking it would be a simple install, turns out isn't (not for me anyway)

Adapter cable for APPLE iPod / iPhone for Audi Concert, Chorus, VW Delta, Beta | eBay

I have the Concert HU
I got as far as taking out the top plug from the back of the HU, then putting in the blue plug from my adapter, no idea where the red or black wire from the adapter goes or what to do with the top plug I first removed.
anybody who has bought something similar or any good with this type of thing, point me in the right direction to getting it to work

cheers
Jord