Download a constellation sheet and print it out. You can print directly onto dark paper, or print on plain white paper and tape or glue it onto your dark paper.
Each of the dots on the constellation represents a star. Using a small pointed object (a pen, pencil or toothpick work well), poke small holes in the dots for each star. (We used this super cool "screw punch" hole puncher, which is great to have if you envision a lot of hole punching in your future.) It's a good idea to put a piece of cardboard under your paper as you punch the holes.
Go into a dark room; hold your paper up to the wall and shine your flashlight behind it. See the stars of your constellation light up!