2002 Dodge Intrepid How to replace the brake light?

I thought replacing a burnt out brake light would be a simple task, so I just went and bought a new light from an auto parts store. But I can't seem to figure out how to get to the bulb! I thought it was something in the trunk behind the light housing. I unscrewed some sort of plastic wing nut that secured the carpet to the area where the light is, but at first glance it looks like it's just a solid piece of metal behind the light! Maybe I'm missing something.

How do I get to the light to replace it?