Take careful notes. While reading your non-fiction book, write down key pieces of information about characters (if there are any), themes and subjects in a notebook set aside for the purpose. You can never take enough notes while reading your non-fiction book. Make sure to include page references so you can refer back to the text later.
Condense your notes. After reading the book you will have a lot of notes. To make this information workable, transfer the most important information onto note cards. This is the time to simplify your information. Combine notes that are sometimes hundreds of pages apart but refer to the same general subject.
Arrange your note cards. You will still have lots of notes that relate to one another but aren't quite the same subject. Group your note cards by broader theme. Begin with the most important subject and proceed to more minor themes you plan to address in your non-fiction book report.
Outline your book report. Take a piece of notebook paper and begin writing a firm outline of your non-fiction book report. This is where your book report will begin to take shape. Your outline should address the overarching themes of the book, the author's personal biography and intent, a summary of the major points of the book, and your personal analysis.
Write your book report. Using your outline, but also referring back to your notes and note cards, begin to flesh out your report. Connect with the reader. Tell a story about what you thought about the subject before you read the book and how that was changed by the information presented, as well as by the author's life story. Talk about how your preconceptions changed after reading the book.
Proofread thoroughly. Make sure there are no typos or misspellings, but also make sure you have effectively communicated the ideas you wanted to get across. It helps to have another person look over your writing before you hand it in.