how do i install my cd player

Make sure the aftermarket unit's ground connection is good.  Sometimes factory head units will be able to use the antenna cable as a ground but when you try to install an aftermarket head unit it will need to have a true ground hooked up.

The ground should be the black wire coming out of the harness, and in that vehicle i'm pretty sure all you have to do is hook it up to the wiring harness you got from Scosche and it should do the trick. Of course, look at the factory plug to make sure that there is in fact a wire coming out of that corresponding pin, into the vehicle.  If there is no wire present then you'll have to run the aftermarket's black ground connection to somewhere else behind the dash. Usually a spot of bare metal will work but again use a multimeter to verify this.

When you test for 12 volts (constant and switched), make sure you do it on the aftermarket head unit's side of the wiring--that way you'll know if the connections you made are good or if maybe they came loose.

oh yea also just to make sure, did you press the "Source" or "on" button on the aftermarket deck?  Almost all head units require you to manually turn it on when it's hooked up, regardless of whether or not it is getting the +12 volts switched signal.  After that initial power-on though, it will turn itself on and off with the car like normal.