If you click with the RIGHT mouse button, you will get a popup menu. This menu is "context sensitive" meaning that it knows where you are, and what you are busy working on, and shows you commands which are relevant to the task at hand.

For example, say you were to click on the Picture Frame tool, and then you deliniate where you want the image to go, but then you forget what to do next! If that were to happen to you, you could just right-click with your mouse and a menu would pop up and suggest a variety of things you could do at this point.  You could then choose from the list what is most appropriate to your needs:  in the example below, we have chosen `Insert clipart´.