What's your central conflict? What's the biggest obstacle life presented that took years to overcome or come to terms with? Maybe it's an illness you were diagnosed with at an early age, a relationship wrought with turmoil, a series of career setbacks, a goal you worked for decades to achieve, or any other number of things. Look to your favorite books and movies for more examples of conflicts.
Understand the memoir genre. In a memoir, you are the main character of your own life story. Many memoirists use the facts of their life story to create an engaging tale for the reader. Because you are relying on your own memories as source material for the story, you may end up describing things differently than others might remember it. The key is to write down things as you remember it, in the most honest way possible. Keep in mind memoirs are different from autobiographies in that memoirs should only cover certain key aspects of your life, not your life from birth until the present day.
Writing an autobiography for a high school or a college English class can help you gain a deeper sense of personal identity. An autobiography allows you to tell your story in a way that reveals truths about your values, goals and dreams. Though there's no exact science to writing an autobiography, you should include information about your background, major events that shaped who you are and any core themes in your life. Include specific examples to help readers understand your life history.