When you dogs pee in the house you tap it not hard but just hard enough to know it did wrong. And say no.
You can buy a spacial like sheet that it goes to the bathroom on that help my puppy learn to be potty trained
It is easier to train your shii poo outside than inside leave your shii poo out side your backyard
If it will go to the bathroom outside, then just put up a special stick marker to tell it where to go that smells like something they like.That attracts it to that spot an that's where it will go.