Hi there,
Easiest way to explain is in the form of a diagram. The Seymour Duncan (manufacturer of pickups) website has quite a clear schematic:
http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=3s_1v_2t_5w
Hope this helps.
Cheers,
Tom
Tom Kennedy, December 2007