2 options I am aware of:
1) There will 2 or 4 screws on the outside around the edges of the tail light lens (cover). Remove those screws and pull the tail light assembly out. You will see wires coming from the coach to sockets in the back of the tail light assembly. The sockets are keyed so turn the CW or CCW to remove, this will expose the bulb and allow you to change it.
2) If you have access to the back side of the the tail light assembly the sockets should be visible on the back side. Twist them out and replace the bulb.
As the previous posted suggested if you could post a picture we could possibly be of more help.
US Navy Vet, Liberty Tree Member of Oath Keepers, NRA & VFW Life Member, Alaska EMT.
2009 Safari Cheetah 40 SKQ
2009 Winnebago Chalet 231CR