The preparation for next lesson is watching the screencast. It is divided into 2 parts due to the length of the video. The first part takes 10 minutes https://www.youtube.com/watch?v=U_avMR07erw. And the second part takes 7 minutes. https://youtu.be/24DqUHb8RRo.
When you still have questions after watching this video you can use the links below for extra information.