First call CS and see if they will continue to collect for you. If he pays say 300. per month and 50. for back support then he will pay 350. per month to arrears. If they will not contact your local court and ask them if the have a pro se office or legal aid. They will also have a law library and they can help you look up what you need. I did do a lien years ago but don't remember exactly how, but it was not to hard. You could also try to remind him he still owes you the money and work out a payment plan, using a possibile lien as leverage. Good luck Cat.