I believe all counties in Florida have early voting for a period of two or three weeks before the actual election date. (We definitely have it in our county and the one next door, and I think it's statewide.) All you have to do is go to one of the early voting sites (usually a courthouse, tax office etc.) and vote as usual.

I don't take advantage of early voting myself since I live in a small rural precinct and have never encountered a line on election day, but I'd certainly avail myself of it if I were a city dweller.