SSL or Secure Socket Layer is needed for enhanced security on a website. With SSL, websites are viewed on the browser with https. To enable SSL, a certificate must be purchased from authorities. Free or cheap ones are available as well like from http://www.startssl.com . However, after purchasing and setting up the certificate, SSL needs to be enabled from the web server - in this case, IIS.
To enable SSL on IIS, open IIS and then click on site under "Sites" and then click on Bindings from the "Edit Site" section.
If https does not exist, add https by clicking on Add like below. Also, select the certificate to bind https to.
After SSL is added, click on SSL settings within IIS subheading for the website.
On the Settings panel, Choose Require SSL.
That should be it. You should be done now.