It is against most state laws for you to drive with brake lights that aren't functioning. When you notice a brake light is not working, you should change it as quickly as possible.
Open the trunk of your car and unscrew three or four black caps that hold in the light. You can unscrew the caps with your hand. Get all of them off.
Have someone step on the brakes. Figure out which one is the brake light. It will be the brightest red light. Turn off the engine to cut off the electrical power.
Take off the back-light assembly by taking out the screws from their holes and disconnecting any electrical connections that might be holding the assembly. Make sure the assembly is all the way off the car, and you can hold it in your hands.
Push the back cover of the bulb you are removing to the left once and pull it out. Be firm with removing the bulb; it likely is in there securely.
Take the bulb out of the plastic holder you removed. Some holders have plastic clips you push in to remove the light. With others, you just have to pull on the bulb. Pull on the bottom of the bulb so you don't crush it and hurt yourself. After the bulb is out of the holder, read the numbers on the bottom. For example, if you have a "1447" bulb, you'll want to replace it with a "1447" bulb.
Put the new bulb in the holder, put the holder back into the light assembly and click it once to the left. Pull on it to make sure it's installed securely. Fit the screws from the back light back into the appropriate holes, screw on the black covers back and close the trunk.
Have someone step on the brakes again to make sure they're working. If not, check the connections and try again.
