Begin by making a simple shape. I made a star, but it doesn't really matter what it is...
Select the shape, and press F8 to convert it into a Movie symbol - call it Star. Double-click
on the instance of the movie on the stage (not the one in the Library box) to bring up its
properties. Give it an instance name of Star1. You might use a different name, but make sure
there's a 1 at the end... you'll see why later.