Wiring up the rear speakers

[Phokus]

Ok I've never wired an audio system before but I'm ok with wiring. How hard is it to do it?

It seems the wiring in my rear speakers have been torn out due to them being all dangly and hanging all over. I saw some speaker wire kinda sticking out under a small piece of trim in the back; in between the lower seat cushion and the door edge. The sub is also not working but as far as I know is in the sub box.
I thought to myself; gee what a hackjob this was.

So since I'm tearing out the entire interior for a black interior I suppose this is the best time to run wiring?

Could someone experienced with this chime in on what I should do and what wire goes where?

edit- oh and this isn't the stock radio it's an Alpine of some sort.

Thanks!

 

[NoSlo]

If you are going to use the speaker outputs on the aftermarket head unit, the right way would be to put new speaker wire in anyway, not to reuse the stock wiring. You just need to route the new speaker wire from the head unit across above the glove box, down inside the plastic kick panel, inside the wiring channels that are about 3" down from the door jambs (you'll need to remove all the plastic trim around the bottom of the door and un-staple the carpet from the body), under the corner of the back seat and up to the speakers. Make sure that the positive and negative are connected correctly at both the radio and the speaker or you will get bad sound. If you are using the stock rear speakers, they have a weird Ford-only connector that you'll have to cut and splice into.