the golden rule in pet-training is "Do not punish, reward!"
First if you catch the dog, pooping inside as said before put him/her outside, second if you and the dog go outside bring along some doggy-snacks, when it does it's bussines reward it with a snack, or whatever treat. This way the dog will "hold it" until he/she is outside to get the reward from leaving a present on the ground. Never hurt or raise your voice to a dog behaving bad, he/she'll actually learn what to do dto piss you off,if the dog is mad, it will behave bad because it will affect your behavior.
Last but definitly not least, don't keep a dog in a small house, when you're out to work all day, that's no way for a dog to live, if you have a garden, make sure the dog can access it when your not home, offcourse make sure he can't escape the garden. If this is not possible, turn on the radio on a low volume so the dog will think he's not alone.
