If not, would I have to transfer the domain name to another web-hosting service with a more robust ability where I can program such a code (i.e.: ASP, PHP, etc.). Thanks!

I also Use Geocities, But There is No Way to have a Password Protected folders

You will need to transfer your site to a hosted location where you can control the server-side logic (e.g. password protection using .htaccess with Apache or a database login).