Browsed county is just about the worst place to learn how to sail as there is very little protected waters.
Why would you want to take sailing lessons there when you have what is probably the best year round, protected, clean body of water in the US: Biscayne bay!
Try the Coconut grove Sailing club. Right on the bay, easy drive at the end of I95. There is an adult sailing program which seems pretty good. I live next door on my boat, we re members and sail our cat boat on the bay all the time, often stopping at the club for food or drinks. Nice and casual, inexpensive Coconut Grove Sailing Club
Or you also have the US Sailing / Laser center also in the grove, on Bayshore