Tick anything you already have, in any order. Quests unlock once this is done.
Lichess lets you set up any position and share it. An engine checks your problem has exactly one solution, which is the difference between a composition and a puzzle.
Open the Lichess board editor2 things left above. Quests are real things you go and do, so they only make sense once you have what you need.
First one waiting: Solve twenty published problems