When you click on the SmartArt icon in a layout or choose it from the Insert Ribbon, you are presented with a dialog box that shows your choices, divided into various categories such as List, Process, Relationship and so on. Choose the one that best suits your needs – you can always change it later (without having to retype anything!) You can also add more shapes if you need four overlapping elements instead of three, for example.
When you add SmartArt, the SmartArt Tools Design Ribbon will appear. Changes made on this Ribbon affect all of the shapes in the diagram. To change individual shapes, go to the SmartArt Tools Format Ribbon. You can add text from either Ribbon.
Change the layout by choosing a new look in the Layouts Group or click on the More icon to see the More Layouts… button and get to the other categories (Design Ribbon).
Change overall look, effects, or colors by using the SmartArt Styles Group (Design Ribbon).
Add text to the shapes by clicking in the shape or using the Text Pane (to the left of the diagram). In the Text Pane, press Enter on the keyboard to get type in the next shape; if you press Enter from the last bullet, a new shape will be added to your diagram.
Change the size of one of the shapes by selecting it then clicking on the Larger (or Smaller) icons in the Shapes Group (Format Ribbon).
Change one of the shapes to emphasize it by clicking on the Change Shape icon in the Shapes Group (Format Ribbon).
Change the Fill or Outline of a shape by clicking on the appropriate icon in the Shape Styles Group (Format Ribbon).