It's pretty simple for a basic handy person. For a true rear-lit frame, you need to make a frame, provide lighting, and a translucent surface for the poster. Think of those X-ray viewers the doctors use. The details, such as finish and hardware, would be to suit your taste.

A frame should be easy to make with 1x4 wood, with a back panel of, say 1/4" plywood. A picture-frame type of door with a glass front would be a nice touch.

The lighting would be easily made from fluorescent lights, either G.E. Brightsticks, Lampi under-cabinet lights, etc., or simple 1-tube surface-mount strips. Alternately, those strips with many tiny bulbs could be used, but the light would be less even.

The poster should be backed with a piece of milk-white translucent plexiglass, so the frame doesn't have to be the exact size of the poster, or you could use clear, and frame the poster with flat-black matting.

Another possibility is to have the poster attached to the back of the frame, and surround the poster with, again, those little multi-bulb strips or rope-lighting, which should be hidden from direct view with a picture-frame-type of frame.

Larry