Hello,
As written in the title, I bought a replica spoiler including brake light like this one :



Including black and red wires,I want to know where do I connect these wires ?

 

I don't recall that that light functioned as a brake light on either of my Nismos. Seems more taillight to me. If it's a taillight (on with headlights and tails of course) or brake light (which makes no sense since it duplicates the CHMSL - center high mount safety light - on the hatch.), you just splice into either of the two circuits. The problematic part is the wire run up through the hatch channel and passing to the CHMSL or, back down to the wiring for the rear light assemblies. Can't imagine this is terribly difficult other than fishing the wiring.