There are many aspects to being a dolphin trainer and all require different backgrounds. It would be best to contact an establishment that you think would be kind you work you would like to do. Will they need a strong public speaker for shows? Would you rather work as veterinarian type role? That will require college work in that direction. Most will require much hands on experience. Perhaps they will have internships available for you to do. Go and find out all the great ways there are to work with these wonderful animals!