Editing Builtin Shaders?

Sorry if this is a newbie question… I couldn’t find the answer by searching…
I wish to edit a builtin shader… I had also downloaded the built-in shaders zipfile. I can open the shader files… But i am not sure where exactly in the project folder it has to be put in… Somewhere like resources/unity_builtin_extra …?

Thanks
Raj

Just somewhere in the project.

–Eric