N. Sanity Beach is the first hub world you'll encounter in Adventure Mode. It serves as an introduction to the game's mechanics and objectives. Your primary goal here is to win all four races to collect their Trophies, which will then allow you to challenge the first boss, Ripper Roo.
Take your time to learn the tracks, practice power sliding, and understand how to use items effectively. Don't worry too much about perfect times or collecting everything on your first pass; focus on winning the races to progress.