To create an activity, choose from one of the following methods:
Using the diagram toolbar button:
Click the Activity button
on the diagram toolbar.
Click on the diagram to create the element.
Using the diagram context menu:
In Diagram view, right click on the background.
From the context menu, select New > Activity.
Using the element context menu:
In the UML Navigator or UML Explorer view, right click on the activity diagram that will contain the new activity.
From the context menu, select New > Activity.