If I have a judgement against ex-husband for unpaid alimony, how can I collect it without having to pay fees?

When you sat "without having to pay fees" do you mean without having to pay legal fees, like to an attorney to collect for you?  You are a judgment creditor and you are entitled to collect in what ever manner the state of Florida allows.  That often includes garnishment of his salary (check to see if Florida has a percentage of income that may be garnished and what that percentage is), file the judgement against real property, levy personal property - whatever the state allows.  There will be filing fees and fees from the clerks for the courts to get certified copies of the judgment for filing, etc.  Good luck to you.

If the ex-husband won't pay voluntarily, you can try to use the various enforcement mechanisms--for example, garnishing wages or a bank account; putting a lien on property; executing (forcing a sale of) personal property. You have the right to do these things yourself--through the courts, of course--as a pro se litigant, in which case you'll have small filing fees but no legal fees. On the other hand, it is not necessarily easy to use the courts; there's a reason why lawyers go to law school for years. If the amount is several thousand dollars or more, you really should consider retaining an attorney to do this--the lawyer will increase you chances of being paid, and also the speed with which you'll be paid. If you insist on doing it yourself, you state or local courts' website should have some forms and instructions you can download. Good luck.