How do you replace the 3rd brake light in a 1997 Nissan Maxima?

if you mean to replace the "top" stop light. the one in the rear windshield, all you do is pull the brake light housing towards the seats, away from the window, it will pop out of place(careful not to pull out the wires) then just replace the bulb and pop it back into place over the meatl guides

If you mean the one on the actual wing outside of the car and not on the inside, I also need that information.