If you are registered as a Democrat or Republican in New York State, September 13 is the day you can vote to choose your party's candidate for state offices. Want to see a sample ballot?
If you live in NYC, you can see your sample ballot and voting site at http://whosontheballot.org.
If you live in another county, Google the county and sample ballot.
Although turnout in primaries is often very low, significant choices are made by the voters in primaries. Be a primary voter!