help for dummy trying to replace mast steaming light

[hockeyfool]

I kept the old original perko brand light fixtures that compac mounted both anchor mast head light and steaming light with mahogany wood base, but water ans corrosion crept in to failure.
So after replacing my mast step backing board for a rebuild of the whole mast step cabin top area, I had to remove a tiny thin strand that was a wire attached to a screw and metal plate .
That I think was a very jury-rigged ground wire. Now that I have 4 wires coming form the mast, I have to decipher why the steaming/deck light has only a red and black wire exiting the hole in mast.
Also, there is a dense stuffing of blown styrofoam all around the hole in mast , looks like maybe through much more of mast as well.
So how do I get my new lights connected ? Do I assume one is a ground or need to ad one somewhere ?