Housesoiling is a spatial problem. Your puppydog has been allowed to eliminate in the wrong place. Housesoiling quickly becomes a bad habit because dogs develop strong location, substrate, and olfactory preferences for their improvised indoor toilet areas. To housetrain your puppydog: first, prevent any more mistakes; and second, teach your puppydog where you would like him to eliminate.
Mistakes are a disaster since they set a bad precedent and create bad habits, which can be hard to break. Consequently, you must prevent mistakes at all cost. Whenever you are not at home, leave your dog in a long-term confinement area, such as a single room indoors with easy-to-clean floors (bathroom, kitchen, or utility room)—this will be your puppydog’s playroom.