Tips for understanding and memorizing a specific book

[raffasw380]

Hello! I have a book that has around 300 pages that I need to understand by the end of September. The book is written in random bulletin points and the themes are jumbled per chapter. I cant really write on the book but I need to understand and absorb each point in the book. I’m having trouble on how I should absorb the information since I know merely reading is not enough. What do you suggest I do? Write in a notebook each point? Would appreciate all the help!