Well I mentioned it already in Chapter 2 at 1:54.http://www.youtube.com/watch?v=FDJFRgW5 ... page&t=111
The 3rd column with keys shows you can change all params, it's exactly the same like for road.
And there is also info in Help, page Terrain, on right.
What else should I put ? Hints, tip of the day
Anyways since now there are plenty presets it's not even needed. Only for size and intensity.