Hello!
Explaining exactly how HTTPS and SSL works is outside the scope of the course. However, it's interesting and I appreciate you may want this information.
Here's a couple resources I think explain things well:
http://robertheaton.com/2014/03/27/how-does-https-actually-work/
https://www.websecurity.symantec.com/security-topics/how-does-ssl-handshake-work
I hope you've enjoyed this section!
Kind regards,
Jose—your instructor