You would sign up for "beginner" classes not puppy classes. Petsmart is fine but if you need more in depth training here is a list of CPDT's - certified pet dog trainers. This is what my trainer has and she also has a master's degree in animal behavior. Her 8 week class is only $10 more than Petsmart, and it's SO worth it!
http://www.ccpdt.com/rstr/TN.html