Im new to wiring so please dont be rude! Okay so this is the wire harness for my pioneer head unit. I want to know if that is a ground? And if it is..isnt the top missing or is it supposed to be like that?

 

That's a ground wire, yes. It's meant for you to like... slightly loosen a random bolt, slide that under, then tighten it back down.

 

^ that. Make sure to scratch up the metal so it's nice and shiny and bare before you screw down the ground

 

I already have a ground for my 12 volt adapter..can i just add this to that or is it one ground to one bolt?

 

Add it. It shouldn't matter

 

I always connect that to the stereo adapter plug you have, it should be fine that way, mind you running it to chassis will not hurt anything its just easier to prewire it the way I do it.

 

I find tec screws work best for grounding

 

Most unpainted bolts that go into the frame or are attached to steel pieces that attach to the frame will work fine. I'm pretty sure you could even bolt it into the steel supports that your centre console bolts to since it's attached to the frame.