Stereo wiring question

I recently bought a '99 Cavalier with an aftermarket stereo that the previous owner totally butchered the installation of. I'm trying to install a new one (they screwed up the other one to the point of not working), but they conveniently hacked out the wiring harness and just spliced the bare wires together instead. So now I need to know what color wires under the dash go to what speaker outputs on the radio. I already managed to sort out the red/yellow/black wires, but I'm totally stumped on the speakers. Any help is appreciated.

i know the blue wires and the yellow ones go to the back of the car. i dont remeber what side but you can just look under the back shelf in the trunk to get left and right for them . green and brown go to the front i think brown right and yellow left but im not 100% sure hope this helps a bit.