What are you doing now? Write that down.
Write the words “Before that…” Then write down something that happened before you were doing whatever it is you are doing now. Try not to plan ahead. An idea will always pop into your head as you write the words “Before that…”
Again, write those words: “Before that…” Again, tell about something that occurred before the last thing you wrote about happened.
Then write the words, “Before that…” and skip back in time again.
You can write about anything. It can be something you did or witnessed, or just something that happened without your involvement
You can skip back a flicker of an instant, or hundreds, even thousands of years. As long as each thing that you write about happened before the last thing that you wrote.
Give your work a title and write the date on it.