Landscape color blending

Hi to everyone, I’d like to know how to obtain this effect on Blender (both images):
http://forum.quest3d.com/index.php?topic=69257.0

Maybe with node material and masks… but I’m completely new to that and I need some help!

Watch this tutorial http://www.cgmasters.net/free-tutorials/splatting-library-linking-in-2-5/