Kodamera on Drupal: How to install modules and themes

As part of my employment at Kodamera, I get to be a Drupal evangelist in many ways. One of them is to make screencasts. The focus right now is the new version of Drupal, Drupal 8.

From the website of Kodamera: "We continue our thorough journey alongside Drupal and explain two ways of adding modules and themes to your Drupal installation. Never install modules or themes from some place other than drupal.org. Other publishing systems have had and are having problems with plugins being available from here and there, and on more than one occasion there have been malicious code in these plugins. I show you the two easiest ways as a newcomer to Drupal to add functionality via new modules and we touch subjects as Update Manager, security and security updates and the commenting module Disqus (which we use here on screencast.kodamera.se)."