You will need:
blackout material (size depends on window)
two thin strips of wood
two wooden blocks (6x6x1 inch)
shower curtain hooks
grommets and a grommet puncher
Measure the size of your windows. Purchase fabric (thick) and blackout material. Include a few extra inches for the blackout material, and at least a foot for the fabric. Measure out and cut both the fabric and blackout material for each side of the window (half of what you measured, length wise).
Place the blackout material over the fabric (have the side of the fabric that you want visible facing out). Fold the edges over and pin them. Then, sew them in place. Be careful, as the piece is usually quite large, and can tend to stretch.
Cut out two pieces of strong wood in 6x6 inch blocks. Drill a hole in the center, the width of the wooden rod.
At the top of your curtains, use the puncher to put in the grommets. The length between the grommets depends on the width of the window, how many curtain hooks you have, and how heavy the curtain is. I did seven inches in between, which proved to work. Make sure that the nice side of the grommet is on the fabric side of the curtain.
Hook the shower curtain hooks through the grommet holes. VERY IMPORTANT - make sure that the shower curtain hooks are wide enough to comfortably fit around the wooden rod.
Hang the curtains of the rod. Put the wooden blocks on the ends of the wooden rod (the rod should be the length of your window). Using the nail gun, attach the thin strips of wood ( also window length) to the two blocks - one strip at the top and one at the bottom of a single side of the block. Take an extra piece of the fabric, 12 inches in length, and, using the nail gun, attach it to the strips of wood. The fabric should be long enough to cover the sides of the wooden blocks, and the extra six inches will cover the top. Nail shelf holders to the wall and then secure the wooden blocks on them. You should now have an awesome blackout curtain. Have a good nights sleep!