Well, something like this really depends on how complex you need it to be.
Do you need to have different files displayed for different users?
What you could do is something like this:
1) Use Snippetmaster to upload the files into the desired folder.
2) Use "Web Protect" utility provided by your web hosting provider to add a password/username for the desired folder.
3) Turn on "directory indexing" for the desired folder, so a list of files will be displayed, instead of a webpage.
Now, when your visitor goes to the desired folder, they'll be prompted for a username/password, and if successful, then the list of files in that folder will be displaed.
Nice and simple.
If you have any questions, let me know.
