Please tell me of a free and easy to use website for organizing an online correspondence chess competition for kids. Thank you very much.
You may want to use the echecsemail website. You can create round-robin tournaments for up to 9 players. For bigger player-pools, you'll have to split them in groups (or maybe talk to the admins).
They also offer the possibility of choosing an alternative starting position (for opening practice purposes mainly)
I hope those kids speak French, though!