I have a 1991 Toyota Corolla. I have removed the stock casette player and have got a sony cd player to put in. I have printed off the table that shows what each colour wire is. I have never done this before so need a bit of help. Where does the black ground wire go? Do I cut off the plug that is in the car, so that a can join the wires from the cd player to them? Do i just leave the wires that I don't need (e.g. amp wire). I only have front dashboard spaeakers. Thanks for any help.