So hard to understand geometry nodes

Hi Yunosuke RRyrie ,

First of all, that's not Geometry Nodes, but Shader Nodes.

But more importantly, it is highly recommended to use the same Blender Version as in the Course (in this case 2.68). (This is especially important, when you are new to Blender.) You can download it from here: https://www.blender.org/download/previous-versions/ 

In this case, however, most of the Nodes used, are unchanged. The only difference is the Musgrave Texture Node, that is now integrated in the Noise Texture Node.

But if you open the file (03_shading_finish.blend) in 4.3, you can see the finished Nodes:

Also if you're a super beginner, this course is not the right one to start on. The very first one is the Blender Basics:

https://cgcookie.com/courses/blender-basics-an-introduction-to-blender-4-x

Then you're off to the Fundamentals:

https://cgcookie.com/p/core

Then people star watching basic courses that set you off to a result, like Press Start, REV or the Sessions:

https://cgcookie.com/courses/press-start-your-simple-first-blender-project

https://cgcookie.com/courses/rev-model-a-low-poly-muscle-car

https://cgcookie.com/courses/sessions-minimalism

https://cgcookie.com/courses/sessions-macro