Once you receive a Summons with a complaint, you need to reply to the Complaint by filing one of two documents:
(1) An Answer. This is your chance to tell the court your side of the story and raise any legal claims you may have against the bank
View this PDF from NYCourtHelp to see a sample Answer Form
(2) A Notice of Appearance. You do not need to tell your side of the story in a Notice Of Appearance. You tell the court you want to participate in the case and that you want to receive a copy of all the documents.
Go to this page on NYCourtHelp for Notice of Appearance forms specific to Nassau County