Simplify the following text for a Grade 7 native English-speaking person.
Original: Ned Flanders and his son Todd first appeared in the season one episode `` Simpsons Roasting on an Open Fire '' , which was the series first episode .
Simplified: Ned Flanders , who was designed by Rich Moore , first appeared in the season one episode `` Simpsons Roasting on an Open Fire '' . The episode was the series premiere , but not the first episode produced .