Tapas basically works with the concept that once you’ve uploaded an “episode” you won’t be uploading new content there.
You can add more pages by editing but like said previously, it won’t notify your subscribers unless you specifically say it should in your editing preferences, and even then most people don’t go back and read it because it’s usually used for things like fixing typos or small mistakes, not uploading new content.
Tapas doesn’t really have the classic smackjeeves-esque “chapters”- I think the best way to catatorize things under the concept of a chapter would be by title.
For example, naming your first 10 pages, “Chapter 1: Morning”, and then naming the next 10 pages, “Chapter 2: Evening”.