I'm 15 and my parents moved away from each otherwhen I was 6 and my dad lives in Florida and my mom lives in Kentucky
I've wanted to live with my dad for the past 9 years my mom won't let me
What do I have to do to move with my dad

Dad has to file a petition on Family Court to change the custody arrangement. The judge will listen to his arguments and your reasons for wanting to move in with him and then make a decision.

You can't really do anything except ask your dad if he wants that too. If he does then he had to petition the court with jurisdiction to modify the custody agreement. You are old enough that most judges will listen to your testimoney but it will be up to the judge and your dad has to be the one to move first on it by filing.