simple, inside the trunk there are two black plastic covers behind the taillights. compress the two tabs and it will come off. you will find that these plastic covers are actually the relays and circuits of the lights. the bulbs are also on it. just push down and twist each bulb counter clockwise. 1/4 turn to get them out. push down and twist clockwise 1/4 turn to put in a bulb.
when done. just put the cover back behind the taillights. just push on it and it will snap in.
btw, all this can be found in your owners manual