The stock license plate lights are usually above the license plate. So, when you look from below, you will see the glass globe that protects the bulb. Remove the globe by unfastening the screws. The bulbs you see will be tiny, and you can remove them by pulling them lightly. If your new bulbs are compatible with the same bracket as the old one, you can pop the new ones in the former bracket, and you will be good to go. Otherwise, you will have to buy a new bracket for the bulb and replace the old sockets. Some large lights will require more power than what a default socket. In that case, you will have to connect the light to a socket inside the engine compartment.