There are a few possible reasons behind a broken brake light. It can be a blown-out fuse, an issue with the wiring or a dead bulb. If you have come to the conclusion that the problem is with the bulb itself after checking the fuse box and the wiring, then you can try replacing the bulb. You should be able to access the bulbs by removing the screws of the assembly. After that pop out the old bulb and replace it with a new one. Unless the new bulb is different from the old one, this is going to be an easy task. Turn on the car and push the brake pedal to check if the new bulb is working. If you are alone, you can place something heavy on the brake pedal to check the lights.