Ask everyone in your family and close family friends for all the details they can remember about your family history and their memories surrounding your birth and childhood. Use a tape recorder and transcribe the interviews later or take notes in a notebook.
Decide who your audience is. If you are much older than the reader, she might be reading to gain a better understanding of that time period. If you are the same age as the reader, he might be reading to reminisce about his own childhood. If you are younger than the reader, your story might hold interest for someone trying to understand a younger generation.
Put your notes in order and make an outline of the sequence of events. Write the story in your own words, as if you were speaking directly to the reader. Begin with your birth, but add information about your family before you were born if that is pertinent.
Write your second chapter about your early childhood. Write a chapter on memories recounted to you by others in your interviews. Start it by saying something like, "My Aunt Cecilia loves to tell the story about when I..." Choose a chapter title that comes from one of the most interesting stories.
Write your third chapter on childhood stories or memories of funny or poignant events that had a significant effect on the rest of your life. Write them as you remember them, recalling as many senses as possible: seeing, touch, hearing, taste, and smell. You can break your chapter up into separate sections if you are telling distinctly different stories that do not flow well into each other.
Continue to tell your stories in chronological order, decade by decade until you reach the present. The number of chapters based on childhood memories, adolescence, young adulthood, middle adulthood, and older adulthood will differ from person to person. The length of each chapter can also vary, as different time periods hold different memories and experiences for you.
Conclude your autobiography with your present life. Summarize how you think your life has been so far. Are you satisfied with the decisions you have made? If you could go back, would you change anything? Where do you think your life is going now? What are your greatest hopes for the future? How do you wish people to remember you?