Journaling can lead you to write personal essays, life stories, creative nonfiction, autobiographies, and memoir.
Journaling is the first step. Then, if you want to do more with your journaling, you can choose to do one of the genres I listed in the last paragraph. But, first, it helps to journal as much as you can and see what develops from there.
Also, keep in mind, you never have to publish anything you write. But, it can sure be enjoyable writing a memoir, whether you publish it or not. Journaling is always the way to start.