Might be a silly question... But how do you make those author's notes boxes?
When you click new chapter/edit chapter there should be three text editor boxes. Author note at the beginning, chapter content, author note at the end.
I'm not sure how it works if you import your chapters, so sorry if that's what you're asking.
If you're asking about formatting code (eg font effects, tables, hyperlinks etc) I believe it's the same type of code as the chapter content.