It is important that your story is formatted properly and to use many paragraph breaks!
A person's speech is usually put into its own paragraph. No paragraph should contain more than 5-10 lines of text!
A wall of texts without paragraphs will be denied!
To add a paragraph break, you have to add an empty line between them.
Add a horizontal line to separate sections.
Embed an image at the current cursor position.
Add a link to another webpage at the current cursor position.
Use the other buttons on the editor toolbar to use bold, italic, underline and other text styles. The preview on the right side shows the effect of your formatting right away.
This Markdown cheat sheet gives an overview of the most common advanced syntax elements (some of the features, like 'tables' or 'code blocks', are disabled intentionally).