There are already some stock wires connected to the stock speakers. When you remove the speakers, you can see what they look like. What you can do is just follow those to where it goes to the end of the door. It's connected to the door harness thing. Look at what are the numbers on those wires that go into the door. Then go to the inside part of the car, where the wires go through (you may need to take off the panels), and you just need to match the numbers. Those are the wires you will probably be working with.
If i don't make any sense, i'm sorry. But anyways, that's what i did on my car. Except I replaced the stock wires with some 16ga wires of my own. I had to pull them out, and put crimps on them, and plug em back in. It was a ***** to do, but it was worth it for the cleaner looking install. Except i ended up wasting it, because i made kickpanels

. Anyways, there are other people on here who could probably explain it a little better. Have fun with your car! I'm having fun right now with my g/f's one, installing components. Later