If you have one, it is almost certainly a fake. If you read the article for the note, it should say that:
"All of the surviving notes have been accounted for, and are currently in the hands of the United States Government.... Forgeries are relatively common, and have sometimes been known to come with fake certificates of authenticity."
Thus, it would not really be worth anything. I would strongly advise not selling it, as there may be legal consequences for selling forgeries in your country.