Helpful Links for Aerospace Education
National Aeronautics and Space Administration (NASA)
United States Air Force (USAF) Information
Note that you can select an individual chapter that may be of interest to you. For example, if you wish to learn about Aircraft Systems, you can select Chapter 6 and read about aircraft engines, electrical systems, landing gear, etc.
Chapters 2 and 3 contain a lot of information, but a skim of the text will provide will provide you with knowledge you can you can use during your orientation flights.