Adding a new item to explorer FILE right-click menu

Question

Hi!
 
I know how to add a new item to the right-click menu of a folder, by adding new entry into "HKEY_CLASSES_ROOT\Folder\shell" key of the registry. But this seems not to work on FILE R-C menu. What reg key i should use to add an item to file R-C menu, not to folder R-C menu?
 
Thanks!