As far as the location of the fs9.cfg, just open the file manager, browse to the C: root, then search for the filename. Once you find it, navigate back up one level and create a shortcut to the folder containing it, then put that shortcut wherever you keep your addon files. This will give you quick access whenever you need it.
Another thing - always, Always, ALWAYS make a backup copy of the fs9.cfg before even opening the original for editing!