To explain it would be like writing a book on the template engine. Download ToG 3.0.0, install the login version and learn how to do it on your own, I'm sorry but I just do not have time to write out a step by step guide. A simple solution would be to not host things on the top level. People wont have access to your stuff if they are protected. You can protect the root of the server, which will prompt login before anyone sees the website, or you can protect all the files and folders on the top level. HFS doesn't naturally support a login page. Just a login prompt.