Welcome to the board.
Don't worry at all about sharks. In general, even seeing one is pretty rare, you make too much noise and don't show up on their preprogrammed list of things to eat. The 2 exceptions I am aware of are nurse sharks and NC sandtigers.
Nurse sharks are common in warm waters like Fla. Unlike most, sharks they are not afraid of divers so seeing them is common but they are also very docile. They are found sleeping under rocks and ledges during the day. It takes a LOT of active provoking to get one to bite you. Don't mess with it and it will ignore you. Don't look into ledges and overhangs and you most likely will never see one.
The NC sandtigers are totally different than any other shark I know of, they seem to like divers..not to eat them but as buddies. While all other sharks avoid divers our sandtigers often pair up with divers or come close to look us over, nothing aggressive, just curious. It is way cool and we have divers come from all over the world to see them. We don't feed them and this is a natural behavior. While very close encounters are common I am unaware of any aggressive behavior being shown and we have lots of divers in the water with them each year.
Bottom line, unless you are at a shark feeding or come to NC, it's unlikely you will ever see on and if you do it will be a shadow in the distance. Most divers agree, seeing a shark is not something to fear but a rare and exciting experience.
I remember some one else ask a similar question a year or so ago. After seeing one for the first time they described changing from fear to excitement. You might want to look up that old thread and read it.