The Index contains all the commands used in the tutorials in alphabetical order. If you need help on the use of a particular command, go to the Index and click on the command that you need help with. You'll be taken to another page, which has an extensively explained definition of the command. After the definition and where you can find the command on the calculator, it tells you where this command is primarily used and explained. Click on that link to the tutorial and you'll be sent to the tutorial that covers that command. After reading that tutorial, you should fully understand how to use that command. The index also usually explains the use of the command more extensively than it is explained in the main tutorial.