Lay two 60-inch planks of 1-by-2 lumber flat on a work surface, spaced 20 inches apart and parallel with each other. This is for a queen-sized headboard.
Abut two planks of 50-inch 2-by-4 lumber on either side of the parallel 60-inch planks. These planks should be perpendicular to the 60-inch planks, with one end 6 inches above the line of the top 60-inch plank. The two 50-inch planks are the side of the headboard, and the two 60-inch planks are the support rails of the headboard.
Glue the ends of the rails to the side planks, then secure them in place with two 3-inch screws driven through the side planks into the ends of the rails.
Apply glue to the face of the rails, then fit 12 planks of 30-inch 1-by-5 lumber across the rails, parallel with the sides. The top of the 12 planks should be 3 inches above the top rail, and 3 inches below the top of the side planks. They should fit snugly along the rails. Let the glue dry.
Turn the headboard over gently, so the back of the rails are exposed. Secure the 12 planks in place with two 1 1/2-inch screws through each of the 12 planks into both rails.
Finish the headboard as desired, either with a wax, oil or matte varnish finish, or a painted and distressed finish if you want the shabby chic rustic style.