Installing aftermarket receiver in 1997 Disco

Does anyone have any tips on installing an aftermarket in dash cd player? Do you just need the wiring harness? Or do you need some kind of converter for the amps? Which wire is the antenna? And what the heck is that big multi-pin connector that comes out of the back of the factory cassette deck? Any help would be greatly appreciated.

I had the same issue, if your going to install a new head unit you have to bypass the sock AMP. I could not find a wire harness that would work while keeping the two 6" subs in the tail gate door working. The only way around it is to get the harness for the head unit and get a small four chanel amp for the subs. Or just do what I did just redue the whole damn thing,keep the highs up front New head unit 4 6.5" speakers and 2 6" subs and a AMP to power them all.