Just type the words, one per line. Example sentences are added for you automatically (see below after saving). Want your own? Add it after a colon: their: The kids rode their bikes.
Optional: put a tricky part in (parentheses) to highlight it: p(eo)ple.

Lists and progress are saved on this device. Safari may clear saved website data if the game isn't opened for a week or more — adding Spell Quest to the Home Screen prevents that. A backup link keeps a copy of everything (open it later to restore).