My ex-husband refuses to pay child support. What should I do to make him pay the child support he owes me?

The first thing you should do is consult with a lawyer.  A lawyer could help you devise a plan that may not even need the court to decide such as sending monthly bills to your ex-husband. If voluntary methods such as this are exhausted, then a lawyer will be able to counsel you on your rights and help you present your case to a court

The court may be able to provide you with assistance from your child’s non-custodial parent by garnishing wages, putting liens on their property or withholding state or federal tax returns.