How to add new items to right-click event on Folders and Files in Windows?

I did google couple of tutorials on google.

I am able to add right-click menu item to a FOLDER by doing this:

[HKEY_CLASSES_ROOT\Directory\shell\Command]
@="TestRightClick:"

[HKEY_CLASSES_ROOT\Directory\shell\Command\Command]
@="myExecutable.exe %L"

I need to add this to a FILE as well.

1) Where do I add it in the registry?

2) And how do I pass parameters to my executable in case if I am selecting multiple files?

Related:

How to pass in multiple file/folder paths via a rigth-click event(verb) to an executable?