Here are the easy directions:
Find a star template and cut out two poster board stars.
Cut irregular pieces from Christmas cards.
Glue the pieces to the poster board stars. It's okay if they overlap each other and you also want them to overlap the edges of the star. Pick a prominent picture to go in the middle of the star that will be on top.
Trim the edges of the star.
Glue the two stars together so that the points are not lined up. You want to see all the points.
Edge with glitter.
Punch hole in top and string them up, or just lay them in between the branches of your tree. Use as an ornament or decoration.