Using the Tools in the Tool Box > Using Annotations Tools
To draw a polygon:
On the Tool Box toolbar, click the Polygon button. The cursor changes to a crosshair.
Click-and-drag the cursor to form the first side of the polygon.
Click again to indicate the end of the first side and the start of the second side.
Continue to draw sides until the polygon is complete.
Double-click to finish; click once anywhere in the image to establish the polygon.