Headboards can be hard to make. Not this one. If you’re not comfortable cutting wood, or don’t have the tools, have the hardware store cut the wood to size.
Lay the 1x8 x 8' next to the long side of the rug then mark the length of the rug onto the board. Cut the board at this mark. Mark the center point of board or draw a line down through the middle. Split the 1x8 down the middle lengthwise. (If you don't have a table saw or circular saw, buy two 1x4 x 8' so dont have to rip the board lengthwise.)
Lay the two horizontal pieces parallel, spaced apart to match the rug's height. Place a 1x4 x 6' at the edge of one of the long frame pieces. Then on the other side, lay it on top of the other piece. Use a framing square and a measuring tape to ensure the vertical piece will fit perfectly in between the two horizontal pieces. Mark the exact length of the vertical piece with a pencil and cut it using a chop saw. Cut the remaining five pieces to the same length. At this point, you should have a rectangle frame with three middle support pieces.
Your frame should now look like this. Hold the frame up to the wall where it will hang. Determine where the wall studs are and mark their corresponding placement on the frame. When hanging the headboard, you'll want to make sure it will be screwed into wall studs.