Speak with senior family members to learn more about your early childhood. Ask if there are specific incidents that they remember or that were most significant to them.
Look up your classmates from high school and college, if appropriate, through social websites such as Facebook. Contact them to request stories they remember about your experiences.
Write down notes about memories as they come to you. Use a word-processing program that will allow you to reorganize your notes as you write.
Include photos. Scan old photos from your childhood and insert them into your word-processing document. Take digital photos of yourself and your family now and insert those in the appropriate section of your document.
Expand the notes you have made into sentences and paragraphs. Describe as much detail as you can remember, unless some of those details are inappropriate.
Print your autobiography and put it into a notebook that others, including your descendants, can read about your memories and learn from them.