you'll need a hole in your engin*** firewall to run it through.
either look for one or make your own with a drill. you'll have to be careful and find a spot that has nothing in the way if you make your own.
after you have the hole you will take off your interior trim pieces along the floor and run the wire underneath them.
once you get to the back seat area run it beside the seat into the trunk.
you'll then drill you or find a bolt already there for your ground wire. if you have a bolt already there take it out and sand off all the paint on the bolt and all the paint where the bolt touches the body of the car.