Hello,
Some people do not like this technique, but it was advice from my vet and it really works. Take a aluminum can (coke can or something) and fill it up with a few pennies (10 or so) and tape the top up. Shake the can when you catch the dog using the restroom in the house and also when the dog messes in the house and you do not catch him, put him next to the mess and shake the can (so he can see why he is in trouble). This method works and it works fast. I trained my puppy in 1 week. But he was just a great puppy. Good luck!