House Training Your Dog
1. Don't give the dog free run of the house, especially if it's a new dog. This is a privilege that needs to be earned with good behavior. At night and when you're not home, use a crate for your dog, making sure he doesn't have so much room that he can "go" on one end and curl up and sleep on the other. (See tip on Crate Training for more info) At other times, restrict the dog to an area where he can be supervised. You can use gates or a tether to keep him in an area where he's always within your view, or tether him to you by putting a belt or carabiner through the handle of his leash and attaching him to you. You don't want him to have an opportunity to potty where you can't interrupt or take him outside before he goes.
2. Give him a schedule. In the morning he goes outside as soon as you let him out of his crate. If he doesn't "go" within 10 minutes, he goes back inside and back in his crate. Give him about 10 minutes, then do it again. Keep repeating this until he goes. It doesn't matter if you walk him or let him out in the backyard, but if you do the latter stay out there with him. As soon as he starts to go (in either scenario), praise him to the skies, calmly. Don't scare him with excitement. You can even give him a treat the second he's done. Depending on his age, he should be taken out anywhere from every 2-3 hours to 2-3 times a day. In-between, he's either in his crate or under supervision. Always take him out roughly 30 minutes after he eats (with young puppies it may be sooner). Don't give him any food within 3 hours of bed time (he can have a frozen Kong or other yummy thing in his crate and he should always have water), and be sure to take him out and make sure he does something before you crate him for the night. If he doesn't go the first time you take him out, give him 10 minutes, put him in his crate and then take him out for another 10 minute try before you go to bed. If you've tried this 3 times and he doesn't go, he doesn't have to so he's in for the night. If he wakes you in the night (keep the crate in your room so you can hear him), take him out, let him go, then right back in the crate; no playing or cuddling.
3. If he starts to "go" in the house and you see it, interrupt him without scaring him and lead him outside by running toward the door, even if this makes a bit of a mess in the process. If he continues to go outside, praise him. If you find the accident after the fact, just clean it up. Showing it to the dog, or worse, sticking his nose in it or yelling at him, only serves to make him afraid of you. Use an enzymatic cleaner to remove any stains and odors so he doesn't have any traces to encourage him to go in that spot again.
4. Be consistent and stay calm. Remember, while some dogs may naturally prefer to "go" outside, most need to be taught that this is where to potty. Just leaving the dog outside without supervision just reinforces the idea that he can go where ever he is and won't give him any clue about where he should go, so be part of the training.