Place a piece of 24-by-40-by-1/2-inch plywood on your work surface. Spray the surface of the plywood with spray adhesive.
Place a 24-by-40-inch sheet of cotton batting on top of the plywood. Make sure the batting is centered on the plywood. Press down to adhere it with the spray adhesive. Let the adhesive dry for 30 minutes.
Cut a piece of 30-by-46-inch fabric. Choose feminine fabrics and colors, such as floral or gingham in pinks and purples. Or, if she is more of a tomboy, choose darker colors and less dainty fabrics, such as checks or stripes in blues and greens. Place the fabric facedown on your work surface. Place the batting-covered plywood on top of the fabric with the batting facedown.
Pull the fabric over the edge of the plywood. Start by pulling the fabric over at the center of the top of the plywood. Place a staple through the fabric into the plywood using a staple gun. Then pull the fabric at the bottom center. Use a staple to secure it. Repeat the process on the left and right sides, pulling the fabric taut as you go. Continue to pull the fabric over the edges and stapling it all around the plywood.
Place the upholstered headboard on the wall. Position it 22 inches off the floor where you want the bed to be. Secure it with a nail gun. Start with one nail at each corner, positioned 1 inch in from the edges. Place additional nails around the edge of the headboard 1 inch in, spaced every 4 inches.
Cut an 82-inch piece of gimp trim. Apply hot glue to the back of the gimp. Press the gimp to the fabric following the nail line on the sides and top. Do not put gimp along the bottom line since it will be covered by the mattress.
Set up your bed in front of the upholstered headboard.