Do I have to save? Does it save automatically?

The editor saves automatically. A couple of seconds after you stop typing, your changes are saved automatically; you'll see the status at the top («Saving…» → «Saved»).

1. 1Edit as usual: you don't need to click anything to save.
2. 2The «Save» button is still there in case you want to force it.
3. 3If the browser closes or the connection drops, at most you lose the last few seconds.

Consejo: You can undo and redo with ⌘Z / ⌘⇧Z (Ctrl on Windows) while the editor is open.