Click the Selection tool in the Tools panel (see Figure 9).
Tools panel with the Selection tool selected
Figure 9. The Selection tool is the first item displayed in the Tools panel.
Click the circle on the Stage to select it. A bounding box selection appears around the circle.
While the circle is still selected, choose Modify > Convert to Symbol (or press F8) to access the Convert to Symbol dialog box (see Figure 10). Enter the name of the symbol in the Name field. Use the Type menu to select the Movie Clip option.
Tip: You can also convert a graphic into a symbol by selecting it and dragging it into the Library panel.