There is nothing inherently wrong with telling your dog “no,” except that it doesn’t give him enough information. Instead of telling your dog “no,” tell him what you want him to do. Dogs don’t generalize well, so if your dog jumps up on someone to say hello and you say no, he may jump higher or he may jump to the left side instead of the right. A better alternative would be to ask him to “sit.” Tell him what you want him to do in order to avoid confusion.
It’s one of those trained behaviors that’s SUPER simple to teach any dog, but really impresses your friends and family. But more importantly, it gives your dog a way to actually tell you he REALLY needs to go potty. This comes in VERY handy when you don’t happen to be in the same room with your dog when nature calls… but with the ringing of the bell, you can hear your dog asking to go outside from any room in your house!
A training class is not there to train your dog. Its purpose is to teach you to train your dog so you will need to be committed to train your dog for short sessions (5 minutes) several times a day rather than just simply turn up for classes! This little bit of training everyday will be repaid with a lifetime of living with a well behaved dog. You will also learn to avoid problems before they begin as well as receive help to overcome any that you already have with your dog.