Use the drawing toolbar ("F", "+", and "-" buttons) and the "angle" text box to draw in the preview cells below the drawing area.
"F" - Draws a line segment
"+" - Increments the angle
"-" - Decrements the angle
Undo Drawing Toolbar Button Presses:
Click the "Undo Last Move" button until satisfied.
Add Desired stage to the Toolbox :
Click the "Add To Toolbox" button.
Draw the Initial Stage in the Drawing Area:
Once a stage is added to the toolbox, select it by clicking on its preview cell. Then click and hold the mouse anywhere in the drawing area and drag it until desired. Release the mouse and the stage is drawn.