AUTOBIOGRAPHY is a piece of composition in which you write about yourself.
So if you want to write a autobiography.
Start with your name,
When were you born.
where were you born,
How was your childhood,
Who are the person who have inspired you,
Who are the person you value most in your life,
what you like to do,
what you study,
where you live,
any important incident in your life.
It refers to anything and everything related to your life.