Keep any background information in the Background Details sections.
The most important sections are characters (WHO), props (WHAT), locations (WHERE) and events (WHEN).
This includes all notes on characters, props, locations and events plus any ideas you want to record.
Each project keeps your novel text and your background notes in one place.
Record information about characters. Keep details of name, age, personality, relationships etc.
Record details of interesting items. E.g. the murder weapon, the painting in chapter 5 scene 3 etc.