How do I file a response to a small claim lawsuit?

I am being sued for some curtains that were removed from a house that I sold. I was not aware that there was a law against removing items i.e. curtains and rods during a sale of a house. Our realtor nor the buyers had said anything to us until after we had signed the documents and moved out of the house about a week or two later at which the items were placed in storage and could not be reached. We are being sued for $1800 for curtains that do not have a value over $80 total if that much, they are about 3-4 years old. We have the items and had informed the buyer previously that once we get items out of storage they will be returned. Also we have already returned the rods. what are our options and now we have 14 days to respond to the suit.