They should be waiting out front for you. Also they will come pick you up from the hotel and drop you off at the airport when it's time for you to check out. When I went to Thailand I booked my holiday with Travel Centre I think it's called and when I arrived in Thailand and got out the front of the airport there were Travel Centre reps there with signs that had my name on. It's probably best you give them a call and find out exactly where you have to go once you arrive in New York.
Oh and have fun