Hyundai Tail Light Replacement Tools:
Phillips head screwdriver
Socket wrench & 8mm socket
Rather irritating that the Owner's Manual gives no instructions about replacing burnt out tail light bulbs. It is pretty simple and saves $$$.
Open the trunk. Behind the tail light you will see a felted cardboard cosmetic cap that covers the access to the 3 nuts that hold the tail light to the car. There are two Phillips head screws holding the cap in place. Remove them and wiggle the cap off. It is held in place on the non-screw side by lip pieces that slide under the cap opening. Remember how the lips slide under because you will have to reverse the procedure when done with the bulb replacement.
With the cosmetic cap removed you now see 3 three metal bolts with nuts. Unscrew the nuts with the socket wrench. Do the last part by hand so as not to drop the nuts.( It helps to spread a white towel under the work area to catch and easily spot anything that gets dropped.)
Now from the outside of the car, wiggle the whole of the tail light assembly off. It is still attached to the electrical cord so be careful not to pull it out too far. On the back of the assembly, are wires leading to each of the 3 bulbs housed into the unit. Turning the gray flange at the base of a bulb to the left will let you pull out the socket and its bulb. After that, to remove the bulb push down on it while turning it to the left.
To get a new bulb you can first put the now empty socket back in place (put in unit and turn flange to the right) and then slide the tail light back into position on the car and close the trunk. It is being held in place by the trunk so it wont fall off. Then take the bulb and drive to an auto parts store or most any gas station that does repairs and get a new one.
Since the tail light assembly is still accessible you can put the new bulb in right in the parking lot if you want to. To put the bulb in, put it into the socket and press down while tuning it to the right. Then test it out. If it doesn't work you are conveniently still at the store.
At home, reverse all procedures to resecure the unit. The hard part is sliding the cosmetic cap back into place correctly by first sliding the lips under and into the opening and then aligning up the screw holes. Luckily the holes are silver metal so you can move the cap around until you can see them through the cap. Put the bottom screw in loosely then check that the top hole is still visible and put in the top one. Then tighten both of them carefully since the felted cardboard they are attached to is rather bouncy and it's easy to think they aren't tightened when they actually are.
Lots of words here, but an easy procedure. My burned out brake light cost $1.50.