Cut the plywood so it measures 62 inches long. This is so the headboard (and footboard) will be one inch wider--on either side--than the queen-size mattress you're using.
Lay your cut plywood foundation piece flat on your work surface, whether that is the floor or a large worktable. Use wood glue and finishing nails to attach two 1-by-3 boards--one on top of the other--to the two short (4-foot wide) sides. The 1-by-3 boards are the "legs" of the headboard, so make sure the boards are flush against one edge, which will be the top.
Glue and nail the 1-by-6 board to the flush edge so it's a straight line between the two makeshift legs. This will be the top of the headboard, and will be used to hold the crown molding.
Glue and nail two more 1-by-3 boards to the bottom edge of the foundation piece. This is the bottom edge of your panels.
Attach the two 1-by-2 boards at 20-inch intervals between the top and bottom edge using the glue and nails. Your panels are now complete.
Stand the headboard up and screw the 1-by-8 to the edge with the 1-by-6 on it, ensuring there's enough overhang for the crown molding.
Glue the crown molding to the 1-by-8, 1-by-6, and around the two edges. Sand the entire piece and wipe it down to remove any dust. Paint or stain your new headboard.
Repeat steps 1 through 7 for the footboard, but cut the foundation piece down to 36 inches from the standard 48-inch height, trim one inch off the four 1-by-3 board used as the legs, and wrap the crown molding all the way around the footboard.