how do you change a tail light bulb on a 1990 reatta

Although I've never experienced this vehicle first hand, common knowledge would indicate that One would open the trunk, removing the molded/trunk liner then access the wire harness. Disconnecting the bulb's socket which is attached to the wire harness, would reveal the bulb socket. check for any moisture, remove the burned out bulb, clean the terminals, replace or install a new bulb. Replace the sock/harness into the light housing. Check the break lights and turn signals there after. However in newer cars, these light housing could be all one piece and one may not be able to extract the bulb. One might have to replace the entire brake light housing.

Well, it's a bit of a chore. Open trunk, peel back liner over lights.Unscrew the plastic wingnuts. Remove the screws on top of the light area. You should then be able to swing the light panel toward you and expose the bulb area. My 1990 has 12 bulbs! Always an adventure. Succes to you in changing bulb(s). Vince