My understanding is that you need to file a form called a quitclaim deed which legally overrides the deed that you now have in effect. You can add your wife's name at that time and have it properly notarized. Then the form needs to be filed with the Town of Hempstead and you'll have to pay some sort of recording fee. I believe forms can be bought anywhere like in Staples, for example.
Any lawyer can do the paper work to add your wife to the deed, preferably a lawyer who specializes in real estate law. This requires some paper work to be filled out and those papers have to be filed at your local clerks office