You will need to contact the local support enforcement office (this is what it is called in my state)it may also be called the child support office or health and human services office. Goggle child support enforcement for your state/county and it should guide you to where you need to go. The office will have you fill out the intake paperwork, it does not cost a cent, and then they will garnish his wages, her child support will come right out of his check, each payday. If he changes employeers the support enforcement office needs to be notified so they can send the support enforcement paperwork directly to the new employeer. His does not have to be late, or behind to ask support enforcement to garnish his wages, it just is a service to make it easier for the parent recieving support to collect on a steady regular basis and never have to wonder when the check will arrive. Some states will actually just transfer the money into your account automatically. Hope this helps.
Most states if not all have a child support division. My daughter had her support set up as a payroll deduction from my grandson's father. She never had to deal with it. I don't know if he would have to be in default or not before you can have this done. I assume your attorney would charge you for doing this. I live in Ca and I know the party who doesn't pay their child support can have any license they hold (drivers license, professional license)suspended. This is a good incentive to pay. My thoughts are with you and your children.
Other benefits to having the state withhold child suppport:
1. They will then maintain an excellent payment record and charge interest on back child support not paid. He in turn also has a concrete record of payment. This is good if you ever have to go back to court and need proof of non-payment.
2. You should be able to intercept any tax refunds he would be getting if he owes back child support. This always makes them mad!
3. If he moves out of state or changes jobs then your state has his information in the system and they will find him pretty quick and one state talks to another state and will automatically withhold child support without you having to play detective.
4. No contact with him to chase down child support and no chance of him giving you a bad check either.