How would I sue my ex-spouse who is a candian citizen? In what courts would you file? I know my ex-wife will not fly in for court, so how would this work? I am a US citizen and the divorce took place in FL.

First, you do not have to sue for this. You already have a judgment. But a judgment is only a sheet of paper.

If your ex has property in America, you can file a motion with the court to have the property attached to satisfy the judgment.

Otherwise, your only hope is if America has a reciprocal treaty with Canada that will compel the Canadian government to give full faith an credit to an American judgment. We have such treaties with many countries, so this is a possibility. But remember, Canada is its own sovereign, so absent Canadian action or property in America, there is nothing an American court can do to compel compliance.

If it's a valid FL judgment, you should be able to file a contempt action in FL and get a contempt judgment. From there, you have the issue of getting a Canadian court to enforce the contempt judgment, which depends on treaty status. Don't ask me what treaty governs the issue, but the US has agreements with most countries that provide for enforcement of foreign judgments.

Sorry if that's not specific enough, but it's also possible that a FL judgment ordering her to pay could be enough to get the collection agency off your back and on hers.

For not paying a debt which is stated in the divorce papers that she was supposed to pay. Now the company is calling me for collection....

sue them for what? That will make a difference in how and what you have to do.