Here is a quick description of each of the icons on the top left side. The best way to learn what they do is to try them out. Remember that the panel in the top right corner will always tell you what the mouse buttons do, and that a right-click will always quit out of the current operation.
Draw a circle by defining the center and
a point on the circle.
Draw a circle by defining two ends of a
diameter.
Draw an ellipse by defining the center and one corner
of the bounding box.
Draw an ellipse by defining two corners of the
bounding box.
Draw a closed curve by defining the enclosing
polygon.
Draw a free curve that fits a polyline.
Draw a closed curve by defining points on the
curve.
Draw a free curve passing through a set of
points.
Draw an arbitrary polygon.
Draw a polyline, that is, a series of line segments
connected end-to-end. A single line segment is just
a polyline with only two points.
Draw a rectangle by defining two opposite
corners.
Draw an oval inscribed in a rectangle.
Draw a regular polygon.
Draw a circular arc defined by three points.
Include a .gif image (Picture
object).
Add textual annotation (large letter T).