Since you already filed the answer, you can file an amendment to the answer.  There isn't any court form.  On a separate sheet of paper, write the name of the case, case number, name and address of court.  Then over to the right it should say Amendment to Answer.The body of your amendment will say, I, _______ (your name) am the defendant in the above-captioned case and amend the answer to the complaint as follows:List the items you want to include.  At the bottom, sign and date under penalty of perjury.  File your amendment with an attached proof of service with the court and mail a copy to the opposing party.If you hadn't already filed your answer, but ran out of room to write all the information, you could have said at the bottom of the answer to see attachment.  Then, you would have attached a separate page labeled attachment to answer and included the additional information.