I have Hong Kong I.D. Right now i live in New Jersey. I want to join the tour to visit China, how can I get the visa to go to china. Can i apply visa in new york?

You can apply China visa through China consulate in New York because New Jersey is under its consular juridiction. You can submit the application in person, if you can't do it, you can entrust someone else (such as your friend, relative, travel agency or visa agency) to do it for you.