How to use shaders in the editor?

If I declare a global shader in my code using the tutorials available, it works, compiles, and UE4 opens perfectly…seems like it should be somewhere, but WHERE?.. I’ve only seen one example where I should create a c++ function that sends data to the gpu, etc.

How do artists use global shaders in the editor? is it in the material editor? Where are the shaders? . I’ve seen people using Custom nodes to add HLSL code, but what if I’ve declared a usf file and loaded it using a class and Macros?
Is it necessary to write a function to send the data and use the shader in the gpu?.

Where is my shader located? Can I see the list of shaders declared and loaded?

Thanks