1989 Plymouth Reliant Repair (third) brake light

Brakes problem
1989 Plymouth Reliant 4 cyl Two Wheel Drive Automatic

My daughter's boyfriend has a 1989 Plymouth Reliant and has to replace the bulb in the central brake light (in the rear window). How would that be done (in simplest terms so I can explain it over the phone.)

And if you can guide me so I can guide him/them on replacing a windshield wiper, that would be a bonus. Apparently it differs from how mine work. ;)