To create a Diagram:
Select first an element where a new Diagram to be contained as a child in Model Explorer.
Select Model | Add Diagram | [DiagramType] in Menu Bar or select Add Diagram | [DiagramType] in Context Menu.
To delete a Diagram:
Select a Diagram to delete in Model Explorer.
Press Ctrl+Delete or select Edit | Delete from Model in Menu Bar or Delete from Model in Context Menu.
To open a diagram, double-click a diagram in Model Explorer.
To open a sub-diagram of a model element, select a model element which contains a diagram as a child and then press Ctrl+Shift+D or select Edit | Open Sub-Diagram.
To close a diagram, click the close icon (x mark) of a diagram in Working Diagrams or press F4 or select View | Close Diagram in Menu Bar.
To close other diagram except an active diagram, press Ctrl+F4 or select View | Close Other Diagrams in Menu Bar.
To close all diagrams, press Shift+F4 or select View | Close All Diagrams in Menu Bar.
To change active diagram, select a diagram in Working Diagram.
To activate the next diagram, press Ctrl+Shift+] or select View | Next Diagram.
To activate the previous diagram, press Ctrl+Shift+[ or select View | Previous Diagram.