Hello

I'd like to have a menu something like:

A
|
-- B
-- C
    |
    --D

and if somebody clicks "D" for example, drupals will show files in some directory (for example "foo\A\D") with a button or other possibility to upload new file to this directory.

Of course, if he clicks "B", drupal will show files in directory for example "foo\B" also with a possibility to upload new files and download existing...

How to do this?