Hi, this link shows how to submit an op-ed to the NYT:
http://www.nytimes.com/ref/membercenter/help/opedsubmit.html
Past experience in the media world (I’m a publicist and media consultant) has taught me that it’s challenging to get anything longer than 750 words printed, so make sure what you’re sending is in the 650–800 word range (they will edit it down a bit if they decide to print it). It’s helpful to have a timely hook for your piece, i.e., current legislation or current events that relate to your topic. For the NYT, having an author who is a big name (politician, writer, celebrity) definitely helps, although it is not 100% necessary. If you can include a sentence or two in italics at the bottom of the piece with your credentials, that may be helpful (only credentials that relate directly to your topic…for example if you’re writing about a health issue and you are an MD, that is relevant, but they don’t need to know your whole CV and/or if you want to Harvard for your undergrad degree, etc) . For what it’s worth, the NYT is one of the hardest outlets to break into for op-ed (you’ll be competing against world leaders and nobel prize winners for space on the op-ed page) so you may want to consider submitting it to your local paper if you don’t hear back from the NYT.
I also recommend reading this piece by David Shipley, who is the NYT’s op-ed editor, on what kinds of criteria are helpful for getting an op-ed published:
http://www.nytimes.com/2004/02/01/opinion/01SHIP.html?ex=1203570000&en=8e7a1fbd7f9bf491&ei=5070
good luck!