You have to study the principles of contract law and have enough braincells to see your defense from those principles (which I'm sure you do) and perform that defense in court.

Or you have to understand bills as negotiable instruments, namely UCC article 3 (codified in FL statutes too, just google it) and know how to perform on the bill with an indorsement and negotiate it by mail to the county  

Ideally both. You can win the foreclosure lawsuit easily if you stand your ground on these facts of law.