Hello Majda,
you don't need to learn all locations and meanings, they are only examples for what we often find to fit. 
When you understand the biological functions of the different organs and tissues, and learn the typical qualities to differentiate between "old brain" and "new brain", you have the working base that leads you to find the appropriate help for the person.
I suggest that you browse the book for inspiration and illustration of the compass. The colours indicate the brain/germ layer that the symptom refers to.
When you find something difficult to understand, please feel free to ask for another explanation!