how do I replace 3rd brake light bulb/bulbs ???

inside car , pry up on cover (2 snaps , 1 each side) then after they are up , pull back towards you to remove lower guides.

This drove me crazy, too. I was told I had to take the seats out to access it, etc., which seemed ridiculous. You need a flat, thin tool. I took a large, flat butcher knife and I gently pried around the light housing. Pry gently so you don't break off the prongs. Wiggle gently once you have loosened it with your flat tool. You will see a wire that leads up to the bulb. On mine it is white. Pinch it gently and turn gently to loosen. Pull the bulb out, put your new one in, snap the housing back in . . . you're good to go.