Fuse Blocks

[LouisC]

As I stated a few times in previous posts, I'm a dummy when it comes to electronics. I'm thinking of adding a fuse block. (Here's where I have no clue). In previous posts I said I was going to add back-up LED lights off of the reverse buzzer. So I was thinking of adding a 10 space fuse block between my volt-2000 reducer and 12v power to the relay (I was told acts like a switch) then to the rear lights. I have 5 wires on the reducer - yellow to switch, 48v + and 48v -, 12v + and 12v -..... The 12v + would go to the fuse block main post. What do I do with the negative 12v wire ??? Then coming off one of the 10amp fuse spaces a 16awg wire would go to my relay then coming out of my relay another 16awg wire go to the positive of my lights....What do I do with the negative wire from my lights ??? Told - not a good idea to ground to frame so I'm a little lost...HELP