Learning Node Editor Shaders for VFX

Hello everyone,

Right to the point, I want to learn how to do effects with a node shade editor as Shader Forge, the thing is that apart from the basic tutorials I do not know how to relate a lot of the nodes between them.

May anybody know where I can find tutorials or info that explain you this kind of things?

And a few examples of what I want to learn but I have no clue about how to start (World Vectors, Screen Positions, Waprs, etc)

Dynamic Geom shader

fx for Chelsea Runner

Thank you so much ^^