In the OrganTutor lesson, Introduction to the Organ Console, you were introduced to various items with which you should become very familiar as an organist.
This lesson offers more help by showing you how to use each item. To begin to really know the organ console, it is best to study this lesson near an organ, where each item can be put to use as explained. If this is impossible, you should at least execute mentally every detail of the instructions given on each screen.
Whichever method you choose to study this lesson, be sure to gain a full understanding of each item, reviewing and repeating as necessary.