The heightmaps created within the Generate function are hardly useful for terrain, which is why the Effects exist. Only the two basic effects are covered here, for more advanced manipulation, look at the Custom Effect Tool [8] topic.
The first of the Effects available is Smooth [6], which ( not surprisingly ) smooths the terrain, creating rounded hills and valleys. The second Effect, called Smooth More [7], is very similar but reduces the sharpness more than the first.