To Add a Context Menu or Menu Item

In the Customize dialog ( File > Settings > Configuration > Customize ) on the Tools tab, expand the Context Menus tab.
Expand the open DGN library.
Expand menus as needed to get to the location where you want to add the context menu or menu item.
Do one of the following:

Select the context folder to which you want to add the context menu or menu item.

or
Select the context menu to which you want to add the context menu or menu item.
Click the New Menu or New Menu Item icon.
Type a name for the context menu or menu item.