Go to the same courthouse you listed on your forms. You can file a petition for child custody in your county's Superior Court.If you are divorcing, the petition will be included in your divorce papers. Generally, you can file for custody only in the "home state" of the child. There are exceptions to the "home state" rule though – see below. FindLaw links to state-specific family law and child custody forms for DIY legal proceedings. Learn when to hire an attorney to help with family law issues. The forms you may need to file include the Petition for Custody and Support of Minor Children (Form FL260) and the Request for Order (Form FL300). In most situations, you can file for custody in the "home state" of the child. FindLaw explains child custody procedures in California, including how to make a parenting plan and how to request custody.