To replace a tail light assembly in older vehicles, undo the screws of the old tail light assembly, remove the cover of the tail light, take out the entire unit, and affix the replacement cover. In newer vehicles, access the tail light, remove its bulbs, detach the tail light from the frame, and replace with a new one.
If the car is old, the screws for removing the tail light assembly should be situated along the sides of the light. Undo the screws using a screwdriver, and pry off the cover of the tail light using a crowbar's tip. Then, gently detach the entire unit without disconnecting any wires attached to it. Replace the cover of the tail light, insert the screws, and reattach the tail light.
If the car is new, open the trunk of the car, and pull the lining fabric downward in the area of the tail light. Locate the bulbs, and disconnect them. If the bulbs are secured using clips, depress the latter to take out the bulbs.
To detach the tail light from its frame, identify the screws situated along the inner side of the vehicle. Use a Phillips screwdriver to undo these screws, and gently pull out the tail light assembly. Press the replacement tail light in the correct position, and replace the screws and the bulbs.