Anne Frank started writing in the confined space of the secret annex in Amsterdam where she and her family had gone into hiding from the Nazis. In addition to her world-famous diary, she also wrote stories based on her school days, when everything was still normal.
Anne Frank wanted to compile her fairy tales and stories into a proper book entitled "Tales and events from the secret annex, described by Anne Frank".
The earliest story in this collection is dated December 8, 1942 and the last one, "The Fairy", May 12, 1944. So she started writing stories at the age of 13 ½ and continued to do so until she was 15. She did not get any older.
Anne Frank's collected stories are available in: Anne Frank Geschichten und Ereignisse aus dem Hinterhaus, published by Fischer Taschenbuch Verlag, (2nd edition 2005) / Anne Frank's Tales from the Secret Annexe, published by Halban, London / Anne Frank's Tales from the Secret Annexe, published by Doubleday, New York.