The tail lights on a car alert cars behind you when you push the brakes to slow down or stop. The exact light replacement process varies by vehicle. Check your car's user manual for specific instructions.
Buy a replacement bulb
Discount stores and hardware stores have replacements for most car tail lights. Ask for assistance or use the computer at the store to look up the right part number.
Unscrew the housing
The bulb for a tail light is often reached through the inside of the rear door. Look for one or two screws that go into the car in line with the tail light. Remove the screws and open the housing door.
Pull out the bulb
After removing the door, the light bulb housing is likely to come out in one bunch. It includes the wiring and bulb. Find the bulb and either twist or pull to remove it. Exercise care to avoid smashing the bulb, which makes the process more difficult.
Attach the replacement bulb and close the housing
Place the replacement bulb in the socket. Push the bulb and wiring back into the housing. Close the door and put the screws back into place. Turn the car on and touch the brakes to see whether the new light works.