If あなた mean posting it on Fanpop, あなた should post it as an article. Chose the option 'Fan Fiction' when あなた are posting it. Obviously あなた should post it in the most appropriate spot, depending on the subject of your ファン fiction.
あなた have to have an account on fanfiction. YOu go to 'document manager' and アップロード your document. Then go to 'new story' and create a new story. I think あなた have to wait 24 hours before あなた can post one though.
