Well I can't say any negative things to you but if you put much of imagination and details on your mind you could come with a story. When I write a story, a lot of things in my mind pop up and I don't where to start. When this happens and I start writing my story, none of my paragraphs make sense and all of them are sometimes "out of order". English class is damn helpful, it's no wonder it required for me in high school for four years. xD If you really wanted to write a fan fiction. Start a setting, create a plot, be detailed about your story as much as you can to give a reader the full imagination from your story.