Securing Website on IIS5 W2K web server

I have a IIS5 webserver running W2K. I recently obtained a Verisign securite certificate for a Novell GroupWise Web based E-Mail site running on that server. I want the site to automatically connect secure (HTTPS) when a user enters the site withouthaving to type the HTTPS header in the url. When they enter the site “mail.***.***.***.***.***” I need it to automatically resolve the url as an HTTPS. Currently, the server returns an error to the user telling them they must enter HTTPS in the url when they use the convention “HTTP://MAIL.***.*****.*****”.
How do I make the process automatic.