I know it feels like you are not making any progress, but.. you have to watch every move they make. take notice how he acts just before he pottys. when you see him act this way, pick him up and take him out the door. when he pottys get excited and give him a treat right then and there.
if he has already went potty, don't make a big deal of it. pick him up and take him out side to let him know that is where you want him to go. he is still young and don't understand what you want him to do.
when Ahia was a puppy I used this method and it took her a while but she will not potty in the house at all now. even during the hurricane when we couldn't go out for a couple of days. I had to take them out the garage door under a bush.
I took notice each time of day that she pooped. around that same time each day was when i took her for a walk. when she pooped I said "good girl! you went potty!" and rewarded with the treat. pretty soon you don't need the treat.
don't yell .. dont' hit... it will only set him back. IMO
good luck.
