All states have agencies that can answer child support questions; in some states, it's the Department of Human Services, in others it's the Department Of Justice. Answers to frequently asked questions and contact information for personnel who can answer further questions are detailed on each state's DHS or DOJ website.
States have varying child support laws, according to Cornell University Law School. For that there are private, family law attorneys practicing in every state who can answer specific questions in regard to local child support laws. Some family law practitioners offer free consultations. Firms offering free consultations can be located through FindLaw.com.