In order to replace a headlight in a Cadillac, you will need the following: a screwdriver and the appropriate type of bulb. There are several different types of bulbs in your car. If you touch the halogen bulb, the oils from your hands will be transferred. Therefore, you'll need to clean them with alcohol, before you place them in the car. Open the hood of your car. Look for the radiator cover. Remove 6 mounting screws. Remove the radiator cover. Remove the mounting bolts. Delicately pull the headlight out. Reassemble. Close the hood. For tail lights, remove the bolts in the truck. Pull back the rug. Remove the screws. Then, the taillight will pull out. Change the appropriate bulb. Reassemble.