Is your lighting system all plastic? If it is, your going to have to find a metal point on the lighting somewhere, maybe on both sides, and connect a wire to it or them there, if the lighting is all metal then you just need one wire. Take that wire from the light point A and now you can screw it into the outlet box, because the outlet box is metal and is grounded, this will ground your equipment, and keep the current from running around. You don't need a GFCI (Ground Fault Circuit Interupt ) in order to ground the light, those are just water safety outlets, like if you have all your stuff plugged into a surge protector, that will act as the same if something goes haywire. But if you don't have a surge protector, then I would have a GFCI installed to plug those things into, other than a surge protector or both, but its not necessary for both.