What is contempt of court?
When a person willfully and deliberately violates a court order without a legally sufficient excuse (such as impossibility) the person is said to be in contempt of court.

So if there are no court orders outstanding and my former spouse is not paying child support, there's no contempt of court?
That's right.

And if my former spouse is in violation of an order, what do I do?
You can file a complaint for contempt of court.

How?
In Connecticut it is just like filing a motion relating to a pending case, except you must have it personally served on your ex-spouse.

How much will it cost?
Connecticut courts recently eliminated the fee for filing a motion for contempt.

Most court actions take forever and my children have to eat. How fast can I get into court?
Usually fast--no more than several weeks in many areas.

Once in court, how do I prove that he didn't pay?
Keep good records and testify about the accuracy of your record keeping.

If the "ex" is in contempt, how soon will I get my money?
Unless your "ex" has a great excuse for not paying, the judge will probably order him to pay immediately or face imprisonment. At most, the judge will give him several days or face arrest.