how can i get help getting a court order for back childsupport?

Your question is a bit vague -- what sort of help do you need? The D.A. can open a case (this costs you nothing) and will --eventually -- have a hearing in the Master's court and attempt to enforce any child support order in effect if the obligor is not paying what is owed. Or, you can hire private counsel to file a motion in family court for arrears, plus interest and penalties, and plus attorney's fees. I would suggest at least a brief phone call to a family law specialist to explain what, precisely, you have (what orders, and what facts) and what you are trying to accomplish.  A much more specific answer can then be provided.