Another terrain question

I have another terrain question.
I saw the menu item to create a terrain.
I also saw the item where you can import an heightmap, but that is not what I want to do?

I want to create a terrain within the model editor.
Does anyone know what I do next after I create the terrain?

That should give you a start:

http://opserver.de/doc/wed/med2/41terrain.html

http://opserver.de/doc/wed/med2/42terraintex.html