As was mentioned, NYC is a big place. I belong to a non profit sailing club in New Jersey, just across the bay. We have youth instruction (9 to 16 yrs) as well as adult instruction and a "loaner boat" program, so you can practice. There are three loaner boats an O'Day 19, a Rhoades 19, and a Harpoon. Prices are reasonable. A few moorings available if you have your own boat.
check riverratssailing.org. We are on the Navesink River just south of Sandy Hook.
Fair Haven, NJ