If you're looking to replace a headlight on your own vehicle, you'll first need to identify the part that holds the headlight. This part is typically called the headlight housing. The headlight housing is usually made of plastic or metal and houses the lightbulb for the headlight. In some cases, the entire assembly (housing and bulb) will need to be replaced. Other times, just the bulb will need to be replaced.
To replace a headlight, start by removing the old bulb from the housing. Once the old bulb has been removed, insert the new bulb into place and reattach any screws or covers that were holding it in place. Finally, test out your new headlight to make sure it's working properly before putting your car back together.