Where does the negative battery ground wire hook to on 1999 Ford contour?

To the frame/chassis and engine block. Either or both There is a place made for it, a simple hole in the chassis for a bolt through the eye terminal on the 1/0 neg black cable or a brass bolt that will take a nut. It will not be far from the battery, the shorter distance the better

Yes there are 4 cables I don't know where the biggest one goes

This is a 1999 contour. I see I think 4 black cables hooked to neg post I don't know what's up with that but be assured at least one goes to the body of the car and another probably to the block..click the picture.