Click OK. A square bounding box is displayed around the circle symbol. You've just created a reusable asset, called a symbol, in your document. In this case, you created a movie clip symbol named my_circle. (For more information about symbols, read Working with symbols in the Flash Professional online documentation.)
If the Library panel is not open, choose Window > Library to access it. The new symbol is now listed in the Library panel. (When you drag a copy of the symbol from the Library panel to the Stage, the copy on the Stage is called an instance of the symbol.)
Animating the circle
In this section, you'll use the symbol in your document to create a basic animation that moves across the Stage: