i have just started rewiring my les paul following a diagram guitar fetish sent me. i have ran into a problem because it says there should be a positive and negative wire coming out of my pickup but i only have one wire. it's an epiphone pickup, any help would be appreciated
There should be a small insulated wire and a bare 'shielding' wire wrapped around it inside the thicker single wire from your pickup like the_line_ said. The insulated wire goes to a switch or a potentiometer (depending on your setup) and the bare wire goes to ground (soldered to the back of a pot).

Bare is -
Wire is +