Like someone has already stated we need more information of what you want to talk about in order to help you to understand how to write a creative piece. But when writing any creative piece i have been advised by everyone single one of my teachers to stay away from stereotypical subjects, like depression and what not, if your going to attempt something like that you need to execute it well.
In every story there needs to be a background knowledge, if your going to write about this little girl you need to know her like the back of your hand. Try starting the story in the middle of it, for example if she was smiling as she walked through a mall, never start off at the start of the story, its too original and mainstream, and for the markers there going to be reading a lot of these pieces per day and will pay extra attention to yours if you don't start like everyone else. Build your story up slowly, have a secret meaning such as the little girl is secretly sad but no one noticed because she always smiled but she only did it to make everyone else happy. This way the reader is already involved reading as everyone else ignores the girl while only they know the truth
Give the little girl a big reason to be sad, make her seem a lot older than she is. You also need to have a plot twist, or a climax within the story, make something happen that would make the reader instantly hooked or form a connection to the little girl.
After having the introduction, middle, climax or plot twist, you can add in another plot twist before ending the story. Never finish the story with "it was just a dream" "And then i woke up" or something ridiculous like that, end the story by not ending it at all, leave it at a cliff hanger and never give the reader a true ending.
Hope this helped