Hey! Welcome to LQ!
You can look in /etc/httpd/conf.d/ssl.conf, or just look around under /etc/httpd for the ssl.conf file. This is what controls SSL settings for apache. I don't know why it's asking you for a username/password when you try to go to the SSL address. I don't think it's supposed to do that. Usually when this happens, its because there is a .htaccess file that's telling the browser to prompt you for username/password. If it's not in an .htaccess file, it must be in the ssl.conf file.
If you have a legitimate SSL certificate from an accredited registraar, you should not see any username/password boxes... it should take you to a webpage, as usual, but with a padlock icon somewhere on the bottom row to indicate you are on a secure site.