Need help installing CD Player in my honda

Ok im not sure this is the right section but I know its some smart cats that are usually in this section. I have an aftermarket cd player my girl got me and Im trying to install it in a honda accord. I went and picked up a wiring harness that fits the indash wiring harness. I crimped all the wires together from the cd player to the wiring harness that I bought. Now my main question is since the harness I purchased has a black "ground" wire and the plug that comes out of the cd player has a black ground wire can I just splice these together and plug it into the in dash harness??? Or do I still have to actually ground the black wire to metal in my car instead??? Any help will be propped

Yes, ground that extra wire to bare metal.

you splice the wires. match the colors. you dont ground those wires unless you want engine noise.