First i watched the videos then i found my own reference image and i sketched the mountain out following the steps shown and once i had the basic shape down i used gouache to paint the mountain, the sky and the tree and grass.

 

 

This is the first  step

This is the make jagged shape and establish shading

This is how the mountainside scene came out with Gouache

I drew this mountainside scene with a faber castel 3b pencil while i was on holiday in canada with the view right in front of me on a coach i did triangles to start with then i made jagged shapes and refining the shape till it matched my view then i added shaddow to the mountain as i saw it then i added trees in dark to light shading. I actually did this one as the coach was moving as well so i am happy with how this came out.