Sky57,

I would definately not punish your puppy because they probably won't know why you are doing so. Unless you catch them in the act you shouldn't even say "no" because they won't know what you're talking about.
If your puppy has an accident that you catch, I would say something like "Let's go outside," and take the puppy to finish out there. Make sure you give your dog plenty of praise too when she does go potty in the correct spot so she can learn to go potty on command.

Pembroke_Corgi