Answering the divorce petition is an important step in your DIY divorce. The purpose of the Answer document is to admit or deny what has been said in the petition. For each paragraph, your answer needs to indicate whether you "admit" or "deny" what is contained in that paragraph.
If you want to file a counter-petition, you must do it at the same time you file the Answer. A counter-petition is the Respondent's request that the divorce be granted and that the court order certain relief.
Why file a counter-petition? If you want the court to order specific things not requested in your spouse's petition, you may want to file a counter-petition. In a previous post we talked about the situations in which you need to make specific allegations in a divorce petition. If any of those situations apply to your case, you may want to file a counter-petition. If you definitely want the divorce and are worried that the petitioning spouse may not complete the divorce, you should file a counter-petition so that you can complete your divorce petition.