The soils in most of Florida are too sandy to raise a highly productive and quality vegetable garden. For better results, raised beds will work well. You can purchase them from Gardeners.com . They supply pre-made cedar or recycled plastic kits. There are many other sources online, from gardening catalogs, or you can build them as a DIY weekend project.
Your choice of bedding is the most important part. We made ours from coconut coir, perlite, worm castings, and traditional compost placed in the layers to form the bedding. The most important thing is that they drain well.
Hint: Lowe's and Home Depot will likely cut the boards for you if you take them the measurements.
I found these instructions and photos to help you at ThePioneerWoman.com.