Your havanese is a playful breed thus her behaviour. A trainer would help for a start, but you would still need to practice the discipline at home, it's just like with kids you know :) school helps only if you repeat the same things at home. It's not a big deal to teach them some basic rules, at least not compared to my stubborn dobermann i used to train! Let me know if you want some tips and i can gladly share with you what i've learned in the dog training course.