New York City is made up of 4 distinct areas: Manhatten, Bronx, Queens and Staten Island. New Jersey is nearby but is not part of New York City.
See map here
http://www.american-n...19-09new_york_map.jpg
Manhatten is an island, and is where most of the tourist attractions many. Many people visit New York but probably rarely venture off Manhatten (except to fly in and out).
There are things in the other areas, but I think it is true to say most of the things are on Manhatten: The Empire State Building, Times Square, Broadway, Statue of Liberty (off shore), Twin towers were there etc etc.
To be honest from your very general questions I think you need to buy a guide book, or at least search for some "New York tourist" web sites and rewad up on it.