Title your autobiography appropriately. No one can tell you what an appropriate title is, but keep in mind the title should hint at what will be learned by reading the autobiography. If the core of your story is how you fell into the trap of drug use and overcame your addiction, consider a dramatic title like "Climbing out of the Pit of Hell: How I Battled Back Against Drug Addiction." Look for a title that encapsulate the core theme of your autobiography.
Write a dedication. This is not necessary, but it's likely you didn't live your life without the help, inspiration or tolerance of others. Surely some people are deserving of thanks in your dedication. The book may be dedicated to a family member, significant other, counselor or teacher.
Write an acknowledgement if there are individuals you want to thank regarding the production of your book. This is different from the dedication in that these are people who may not hold a special place in your life and in your heart, yet they have contributed in some way to getting your story written and published. The acknowledgement is typically longer than a dedication.
Write a forward and introduction. The forward will typically tell readers why you decided to write your autobiography and what you hope to accomplish by it. The introduction will tell readers what the book is about. The introduction is designed to hook your readers.
Write the body of your book in chapters. The chapters are numbered or individually titled in a way that indicates what the chapter is about. There is no set way to present your story. Some writers go for a linear approach, beginning with youth and moving into the later years. Other writers begin with the present situation of their lives and go back in subsequent chapters to show how they arrived at this point in their lives. The purpose of the story and the effect you hope to achieve play roles in dictating this part of the writing phase.