I started out with a basic horizon line, green landscape and blue sky Using the clipping mask feature I created some shadows for the left hand mountain, its the main tool I use to shade in phtoshop and looks really effective on things like mountains A few different shades of green for the middle mountain, but again the same process Along wiht the right hand mountain I added a new overlay of green for the floor The drab lake runs through the middle of the mountains as that was specifically included in the text Here is what the scene looks like now the filters are on Ive added some grass in the foreground to make use of all the green highlands