Hold two 3/4-by-4-by-36-inch boards upright on their long, thin ends, parallel to each other with 8 inches between them. Set two 3/4-by-4-by-8-inch boards between them on either end, so that the four boards form an 9 1/2-by-36-inch rectangular frame.
Drill two holes through each of the larger boards and into each end of the smaller boards for a total of eight holes. Set 2-inch wood screws within each hole and attach them in place tightly.
Have an assistant help position two 3/4-by-3-by-8-inch boards over the shorter boards of the frame, so that they cover the top of the shorter boards and stick 2 1/4-inch out away from the frame. Nail them in place with 2-inch finishing nails every two inches.
Repeat with two 3/4-by-3 by-40 1/2-inch boards over the long frame boards, so that the original frame is not topped by a 14-by-40 1/2-inch wood frame that resembles a picture frame.
Turn off the fuse for the fluorescent light. Remove the light fixture from the ceiling, leaving it dangling if necessary. Use a stud finder to locate and mark the studs and other wood supports around the recessed light area. Position the frame in place so that the top section is flush to the ceiling and the frame slides into the recessed area.
Drill holes through the frame and into the markings for wood studs. Attach the frame to the ceiling with 2-inch wood screws. Reinstall the fluorescent light fixture.