I used 18 gauge automobile hookup wire from the local auto store for this step. My bike had two brake levers so I cut the two wires long enough to meet up with the ones from the other lever at the bicycle stem. Trim 1/4" of insulation off each end using a wire stripper. Feed the wire through the hole in one of the switch leads going from the inside to the outside. Once through, bend the stripped section in half and then solder it to the lead. Repeat with the other lead. Use heat shrink tubing that just fits over the soldered connection and cut two 1/2" lengths of it. Slip one over each wire till they cover the soldered area and use a heat gun to shrink the tubing in place. Use a larger piece of heat shrink tubing that just fits over both wires at the switch and cut it to 3/4" length. Slide it over both wires till it butts up against the switch and use the heat gun to shrink it in place. Now wrap the two wires in electrical tape to keep them together and protected. Screw the switch back into the brake lever.That's it. Now it's up to you to figure out how you want to wire up a brake light. This tutorial only covers making the brake switch.