You can use the grid, the rulers, and guides to position shapes one by one, but what if you've got dozens of shapes in your diagram? The Distribute Shapes command on the Shape menu will get you home in time for dinner.
Let's say you've got the shapes you want on the page, but one is too close to another, and another is too far away. The ideal arrangement is to have an equal amount of space between all the shapes. You can do this in three steps, without any fussy mouse work.
Just select three or more shapes, click the command, and choose a distribution option. In this example, a horizontal distribution button evened things out. You'll get a chance to try this in the practice session.