Choose from any of the methods listed below to create a subsystem.
Use the diagram toolbar button:
Click the Subsystem button
on the diagram toolbar.
Click on the diagram to create the element.
Use the diagram context menu:
In Diagram view, right click on the background.
From the context menu, select New > Subsystem.
Use the element context menu:
In the UML Navigator view, right click on the component diagram that will contain the new subsystem.
From the context menu, select New > Subsystem.