So since you are on a mobile device you need to go on the fanfiction website

Next scroll to the bottom of the page, you will see a link called:

Desktop/tablet mode highlighted in blue

Click that link ^^^^^ that reads exactly as above

After that you will need to login, once you've logged in click on your username it is in the top right hand corner of your screen.

After clicking the page will look something like this : Tabs on the left side of the page saying Account, Publish, Private Messaging, etc.

Your going to click the tab that says Publish then Document manager.

After it will load. Up a page with

Label: label your story

Method: Choose copy-N-paste

After you choose copy-n-paste your goin to start typing the first chapter, after you finish typing your going to set format leave it at story once you have finished your chapter make sure you proof read and put up a authors note telling your readers you do not own all rights reserved to the company and creators of ...

Also good luck

Click submit doc