Select the Decision Tree template from the Tree Diagrams category under the New Document view on the dashboard.
Your template will already have a basic decision tree on it with three shapes: a decision followed by two outcomes.
Select any box and type to add text.
To add more decisions and outcomes, you can use Quick Add Controls. Hover over an existing shape until you see the yellow arrows appear around the shape.
Click on a yellow arrow in the direction you want to add a new set of outcomes. Clicking the arrow will add two outcomes automatically connected with a yes/no line to the previous shape.