The Diagram part shows different aspects of the simulation database using graphical paradigm.
The toolbar on the left offers all objects user can drop on the Diagram area for code generation.
To drop an object on the area, click on the toolbar symbol then click on the Diagram area to drop it at the mouse position.
Object can be edited by double clicking, or right clicking then choosing Edit or Properties, or by using the

button.
The Diagram part reflect the selection of any item of the Environment list.