That's a very odd and inappropriate behavior. It could be that the younger dog pees when he gets excited or nervous, or it could be that he means to mark the older dog as "his property" or something. The only way is to get a dog trainer or your vet involved to understand the context and symptoms to then decide on a course of action to correct the problem.
Your younger dog is trying to be dominating the older dog.
no silly willy bob
Yes, a young dog can learn from an older dog. the young dog does not have to be young. just younger than the older dog.
He is marking her as his property.
Teaching an older dog would take more time than teaching a younger dog. This is because the younger dog's personality has not been molded yet and would not be difficult to change or train to become the dog you want it to be when it grows up. While the older dog has already developed its own characteristics or personality and would be difficult to start from scratch and change it as the dog has already been used to who it is.
It is probably trying to dominate. Because the puppy is younger, the older dog wants to show it that they, (the older one) are the boss.
It depends on the dog
He had older and younger siblings.
well if you dont want your dog to urinate on your belongings or stuff then train your dog not to! There are also books to help you.
it is to show dominance over the other dog.
its not trained
He or she is excited.