A "letter to the court" is not the proper means of responding to a summons and complaint. Rather, you need to draft and file an Answer. You must also send a copy of that Answer to the plaintiff.
As for forms, many attorney's would charge you only a small fee to prepare an Answer for you. However, you would be hard-pressed to find an attorney who is willing to give you a blank "sample" form. If you are unwilling to pay an attorney to prepare the form for you, you will have to take to the web instead.
Good luck; and I hope this information helps answer your question(s).
~ Kem Eyo
ONE ADDITIONAL PIECE OF INFORMATION: "I cannot afford to pay" is almost never a viable defense to a debt.
The above answer is a general explanation of legal rights and procedures. It does not constitute legal advice. Nor does it establish an attorney-client relationship between the individual posting the question and the attorney providing the answer.