When making a new story or chapter, what do you need in your notes?

There is no requirement on the author notes. You can put as little or as much as you want there, although too much and people will just ignore it.

883947 what he said

883947. You don't need anything. Author's notes are optional.

883947 The only thing I've seen consistently in author notes is thanks to editors / cover artists / etc. But other just put that in the description.

For ANs? Nothing, you don't have to have them. Main thing is the ANs should only take up a small amount of space

Mostly I use the author notes to point out something interesting - references or the like and give out thanks to the people who assisted with editing or proof reading.

If it going to be longer than a few paragraphs, 2-3 at most, then I would consider making another chapter titled as authors notes/comments.

883947
If you do choose to put something in the authors notes, don't forget to put color tags around to turn the text black. This way, it becomes readable for those who read with a dark background.

I usually just use the notes to say thanks for reading or if something comes up in the story I feel I should talk about...it's your choice what you put in your notes

Honestly you could put anything you want or nothing at all. It's up to you. My advice is always to keep the author's note short, sweet, and relevant to the story.

I will confess that I have had long Author's notes in the past, but if it's telling you something important about the story then it's okay, but you should either make that a whole other chapter, or say in the beginning of the note: THIS WILL BE A LONGER, BUT REALLY IMPORTANT NOTE, SO PLEASE DON'T FORGET TO READ IT!