first: you should be good at HTML.
the template of HFS 2.2 sports a separated upload page.
You can learn from it, or start from it. I'm attaching it here for your convenience.
You can learn more details at this page
http://www.rejetto.com/wiki/index.php/HFS:_TemplateTo upload to a hidden folder you can either
(1) upload directly to the folder, and hide just its content (not the folder itself) as in
as having the page at
http://my-hfs/hidden-folder/~uploadyou can hide the content by setting a files-filter to \*
* is for everything, and the initial \ works as a negation.
(2) upload to any folder, and then use command {.move.} to move the just uploaded file.
You may put it in the [upload completed] event or in the [upload success]