The three wires are attached to a plug that is at the base of the headlight itself. This plug will be held in by a plastic catch, a metal clip, or in some cases a screw cap.
For a plastic catch, you'll see a little lever sticking up at the top of the plug. Press this down with your thumb while you pull firmy but gently on the plug. It should slide off.
For a metal clip, just pull up and away and it will come off in your hand. Try not to drop it, when these things hit the pavement the clips are like stick-bugs in the woods, hard to see.
For a screw cap, simply unscrew it by turning it counter-clockwise (the old righty-tighty/lefty loosey might get confusing since you are doing the reacharound.)
