Like human babies, even puppies have weak bladder which means they can't control their pee for long. You need to take the puppy out as often as possible- immediately after play, when the puppy wakes up from sleep and at least once in the midnight.
You can identify a place in your house where you want your dog to pee, it can be anyplace like on the roof, empty area in the house. You can cover up the area with newspapers. Take the puppy to that place as often as possible. The puppy should start peeing in that area. When he starts doing, you should reward him with treat at the same time.
You can also use clickers to potty train your puppy. For any further help/clarification, you can also contact me on https://www.facebook.com/navjo t.singh.92560281