the FileManager User Cheat Sheet

screenshot.

pointing at the different panels, their names and use.

Actions: select / rename / move / copy / delete / upload / download / browsing the directory tree

keyboard shortcuts.

mouse shortcuts: click and doubleclick in the directory detail view

---

plus (in fine print) a checklist who you should complain at when one of the features above are missing (security / access rights / enabled features / lacking features / known bugs)

or rather not clutter a good cheat sheet with that mumbo, but point folks at the FileManager Actions' Security Check.