If you don't understand what the legal stuff means you need a lawyer to explain it to you. You are in a mess, and I understand that it is frustrating and intimidating, but this isn't a do it yourself project. If you don't have money, try and borrow it, sell things you don't use, get a second job, something. But you really need to get a lawyer. I will say after glancing at the document that it appears that they are reviewing to change the child support order, but I didn't see anything that would discuss the arrears.
At the very least you should meet with one and get some advice even if you don't retain them. You will likely have to pay an hourly fee, but it would be worth it to have a game plan.

