It all starts in the center if you want power.

The carbon, or chrome ring around the sound system is snapped into place. Reach down as low as you can and pry the bottom corner loose. This will make the rest easy. The radio is held in with 4 screws, and all wires (heat, esp, etc) will unplug. It may be hard to undo the bottom corner with just fingers, so I would wrap some black take around the end of a short flat head screwdriver and use it to get started.
Good luck