Web Site security

I currently have a web site (MS Win XP Pro) that was created using MS Front Page 2003 I need to add security: I would like for a User ID and password be required to go past the main page. I would like for a new visitor to enter information: Name, Address, Phone, email, User name and password. They would submit this information and I would approve or deny the ID and password. I would also need a check to prevent duplicate User ID’s. They would need to be able to update their information if needed.