The blender file is well documented with short text explanations.
Here is a short how-to guide:
Each of the Halftone-Nodes needs an RGB input value or a single value between 0 and 1.
I've prepared some input methods for standard use cases and added a short explanation to each of them.
Currently some of the inputs only work with Eevee and some only in Cycles. Of course you can create your own input values or even use a plain texture.
It is critical to adjust the Brightness and Contrast of the Haltone Nodes to your specific needs. Sometimes it is even better to use a Colorramp or an RGB Curve between you RGB input and the Halftone Node.
Each Halftone-Node outputs an RGB value.
If you want to use the nodes in your project, i recommend appending the materials or the individual node groups to your blender file (File > Append). Then you can simply copy & paste the nodes you want to your material.
I've also added some example shaders. To view them you need to make the "ExampleShaders" collection visible.