In the tree view, right-click the top package in the model you want to add a diagram to.
Point to New, and then click the type of diagram you want to add.
When you add a new diagram, a new icon appears in the tree view and a new drawing page and stencil with the appropriate shapes opens. A watermark with the name of the diagram type appears in the workspace.
Note: Statechart and often activity diagrams are associated with particular classes or use cases. To add a statechart or activity diagram to a model, right-click the appropriate class or use case icon in the tree view, point to New, and then click the type of diagram you want to add.
You can also add activity diagrams by right-clicking a package, pointing to New, and then clicking Activity Diagram. You can create static structure diagrams by right-clicking a class icon.
Tip: You can also add a diagram to a model by right-clicking the drawing page for an existing static structure, use case, collaboration, sequence, deployment, or component diagram, and then clicking Insert UML Diagram on the shortcut menu.
Add a diagram to a UML model