The Diagram editor displays the diagrams associated with your project. In this editor, you create, edit, and delete diagram elements for your UML model.
You can populate a diagram with new model elements such as classes, packages, and interfaces in two ways:
You can import an existing model element into a diagram by dragging the element's node from the Projects window into the diagram.
Find the Diagram editor's pop-up menu options by right-clicking the background or a selected element.
Any element you select in the Diagram editor is reflected in the Properties window and the Documentation window.