I agree with the others about getting a nationally accredited certification. Go for one of the better certifications and you will be happy you did.
In addition, I would suggest finding an instructor who can serve as a mentor to you. There are many skills that go into in teaching fitness classes in (cueing, monitoring the room, suggesting modifications, sometimes teaching to the beat of the music, motivating the class, etc…).
Perhaps take a few classes and find an instructor who has the qualities you admire. A mentor can help “teach you the ropes” and advise you in these areas.
Good luck and have fun–it is very rewarding!