Create characters to use them for the dialogs. > Character item contains their ID, name and icon url for easier management
Structurize your story into chapters, then each chapter should have scenes. > Chapters item contains ID, name, scenes
Break down chapters into individual scenes. > Scene item contains ID, name, chapterId. For scenes within scenes just number the scenes in order: Scene 2, Scene 2.1, Scene 2.1.1, etc.
Assign speech to characters within chapters scenes. > Dialog item joins all of the defined items togheter. So for example you want to add dialog to Chapter 1, Scene 1. You select which chapter and which scene in the selector, then you can add dialogs for that chapter scene, and define which characters are talking in order.
Export all items to json files. > Then hook them up in your game. Read my blog on how to do it for unity engine (coming soon).