when your done striping the wires you should have 3 different colored wires they should be gold, green and red(or atleast the 3 headphones i tryed were)if it had four twist the two golds together.Gold is ground, green goes to the tip of the jack and red goes to the ring in the middle of the jack. if
you don't have those colors put some solder on each wire then test each wire with a volt meter to figure outh wich one or ones are ground(plase one end of the meter on the solder and the other on the thick ring on the jack. move the tester from one solder point to the next untill the light lights up.
I used speaker wire to exten the wire(10ft)you need three wires and should strip about two inches off each end of each wire.
if your going to heat shrink the wires indevigualy(recomended) place the heat shrink tube over each wire. If you have 2 grounds twist them together then wrap them around one wire then solder them on. make sure the solder touches bothe wires together. Repeat this for all wires.