Lay two two-by-fours parallel to each other, separated by a distance as long as your stage. Place two more two-by-fours perpendicular to and over the first two so the ends overlap, forming a hollow square frame.
Connect the wood frame by inserting wood screws through the corners of the frame. Use three screws for each corner to make it secure.
Stretch a piece of canvas over the face of the frame. Nail through the canvas and into the top two-by-fours of the wooden frame at 3-inch intervals. This will stretch the material taut and allow you to create an attractive backdrop.
Paint the backdrop with stage paint. Make it black or a very deep blue. Allow the canvas to dry before you move it.
Lift the frame onto its side so it stands tall. Place L brackets against the two-by-fours on the back of the frame. Screw them in place so the frame can stand alone.
Pierce the canvas with sharp nails or knitting needles. Pierce it sporadically to get a realistic night-sky look. Use needles of varying sizes so some are larger than others, just like real stars.
Place the backdrop on the stage. Space the backdrop at least four feet away from the back curtain of the stage.
Set two stationary spotlights behind the backdrop. Position the lights so they focus entirely on the back of the backdrop, creating as little leaked light around the sides of the backdrop as possible.
Turn the lights on and step out in front of the stage. The light will shine through the holes in the canvas, lighting up each of the stars.