Presuming you're talking about an airstone, most people agree that you shouldn't use one. You can do a search, but the consensus seems to be that they cause salt creep (when the bubbles burst, they leave deposits of salt on your glass that you don't get with fresh water), they act as a protein skimmer except that the foam is now just sitting in your tank, and that if the bubbles are small enough, they can be harmful to your fish. I know some people will disagree about if they are harmful, but you certainly don't NEED one like you do in a freshwater.
Oh, and welcome!