Redirect URL AND http to https

I am trying to figure out how I can redirect requests to
http://www.mydomain.com/subfolder to https://www.mydomain.com.

This is an Apache web server running on a Windows 2003 (hope you will
still help) box.

I am pretty sure it's something in the httpd.conf file, but all of the
docs I have read are pretty confusing.

Right now the only way users can hit the webpage is by going to
https://www.mydomain.com/subfolder. If they go to https://www.mydomain.com
they get the main Apache page. We want to redirect all http requests
to https as well.