Hi Yunosuke @Ryrie ,
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:
