As you work in the application, you may wish to be aware of how things work generally.
The main editing area for Views is in the central-right portion of the application. Windows and tabs can be dragged and dropped to be re-arranged as you wish. You can even detach some windows so that they "float". If ever you wish to reset the arrangement of windows back to their default positions, choose "Reset Window Layout" from the main "Window" menu.
Full Undo and Redo commands are available for every action that is performed by the user in Archi.
Undo and Redo commands are contextual depending on the selected model in the Model Tree or a View. Clicking onto a View or the Model Tree will enable the command if an action has been performed for that model.
Contextual and full help is available from the main "Help" menu. On Windows pressing the "F1" key will invoke contextual help.