Use chapter divisions to give the book structure. Chapters are useful because they allow you to move on from discussing certain life periods or events. There's a reason we have the expression that we've "closed a chapter" or "opened a new chapter" in life, and it's even more applicable when discussing an autobiography. Chapter breaks allow you to skip forward 10 years, go back in time, or start describing a new theme without jarring the reader too much.
“I was born in 19XX year, I entered school N…” Would you read that if you had a choice? Most likely not, especially if you already have read a dozen biographies which star with the same phrase. Yes, an autobiography is a formal piece of writing. But here, it rather means that you are not allowed to use slang and colloquial language, instead of following a specific pattern of writing.
Below, you’ll find an example of an autobiography provided by one of our experienced writers. You are welcome to use it as a template for your own autobiography. Although you can borrow some ideas about proper structure and writing style, you can’t copy our sample without citing it properly. Please, don’t commit plagiarism! We believe that you are able to create an autobiography that will be no worse than our autobiography example for high school students.
Why it helps: First off, if you want to write a memoir, this three-sentence description will form the structure of your book. In effect, it’s a supershort story of your life—a beginning, a middle and the now, if you will. Even if you have zero impulse to write another word, however, the exercise can show you how you view yourself, your past and your present, all of which can inform your future. Unless, of course, you change the narrative—a privilege granted to any writer. 

You may not have had the most interesting childhood in the world, but everyone has had a few memorable experiences. Highlight the best parts when you can. If you live in a big city, for instance, you should realize that many people who grew up in the country have never ridden a subway, walked to school, ridden in a taxi, or walked to a store a few blocks away.
Conduct basic research. Depending on your story, you may feel you need to do in-depth research on a certain subject, like air force pilots in WWII or life in a refugee camp in Poland. However, resist doing too much research before you start your first draft. You may get overwhelmed by the amount of information you come across during your research and start to forget your personal take on the facts. Remember that your memoir should focus on your memory of the event, rather than be purely factual or completely accurate.[7]

When you are done with reading and have reached an inspiring mood, you can try to write. Then comes the question on how to organize time wisely and your text, in order to present it in the best way possible. Such questions you may face while writing and after the first draft is finished. We have worked hard and found for you some sources that will be helpful while writing an autobiography.

Develop a central theme, main idea or thesis that clearly explains the purpose behind your autobiography. For example, your theme might be about how you overcame obstacles to become a stronger person, or it might explain why a particular passion -- such as mountain climbing or rescuing animals -- is so important to you. Back your theme with details and background information about your life experiences. For example, you might explain that your dad is in the military, so you've had to learn how to adapt quickly to new schools and unfamiliar environments. Or, you might discuss what it was like growing up in a poor, single-parent home, but how your family was always willing to take in injured or stray pets.