My ex-husband is not paying what was ordered in our divorce decree, what can I do?

You can take him to court for violation of a court order.  He can be fined and jailed for contempt.  It will be up to him to prove that he cannot not make his payments (and possibly have them reduced).  However, you can counter with the fact the he is taking side jobs and has money for "luxury" items; the TV and firepit would qualify.  Just try to  get as much evidence of all of this as possible so you can present it to the judge in court. 

Typically, states provide free legal counsel for such cases.  If not, contact your state's Department of Social Services, they may be able to refer you to free legal services.  Otherwise, see if you qualify for Legal Aid or see if they can recommend someone to help you.  Also, check if there is a law school nearby to where you live; they typically run free/low cost clinics that handle these type cases.  Finally, contact the local Bar Association in your county; they may have a list of attorneys who will take your case "pro bono" (for free) or at least for a reduced fee based on your income/circumstances.