There is not a tutorial that would work for this specific scenario of securing files for only specific users, but the login functionality and the ability to secure pages and identify the logged in user can all be created for you automatically with Security Assist using the wizard.
Once you have that in place you would want to make sure you have your admin back end setup to associate files with users. Then finally you would create the file listing page for your users. On this page you would have a recordset that filters for only the logged in user, this way they can only see their files.
This is just an overview of how you could do this, please post back with any other questions that you have about this.
