Ditto on everything Glacier and Clara said. Her behavior is a big reason why dogs get turned into shelters in the first place. They go from being cute little puppies with no manners (but who cares it's so cute) to puppies in a grown dog's body with no manners (now it's not cute). She's depending on you to teach her how to properly behave. Don't worry about how she's going to act in public when you start a training class. If the other people in the class had well behaved dogs, they wouldn't be in the class either.