PHP redirect & url rewrite

PHP redirect & url rewrite

Tried already a couple of ways using url redirect, but I am, no good in php.
I have the following problem: The sub folders & files of my server are
case-sensitive. Example: www.example.com/Folder/index.html
How can I make them case insensitive, or redirect alternative spellings to
www.example.com/Folder/
I also want to hide the actual url of all subfolders and files, e.g. only:
www.example.com/Folder should be shown, not any sub-items.
I have no CMS, only static HTML pages.