You may need to enable HTTPS redirects from Configuration > System > Settings > Domain. Just keep in mind the when a user tries to reach Facebook, for example, but instead get send to our page, the browser is going to display a security warning. Also note that HTTPS redirects are a very taxing process, and it may cause adverse side affects within your system. Given this information, you really have two options.
- Educate your users to continue past the warning.
- Educate your users to browse directly to the login page to continue.
Notice that both options include educating the user base. The choice is yours.