When we first got our dog (10 month old rescue pomeranian), we got just so far in housebreaking her and couldn't get any further. We could tell that she wasn't getting the message clearly on what we wanted and we were sort of at a loss on how to let her know that she'd done something wrong without yelling or (god forbid) hitting her.
Then we had a brainstorm. We stole an idea from my (human) nephew's training and now have a "naughty seat" for her. The premise is that the child must sit on the naughty seat for a couple of minutes whenever he has done something wrong. We converted that to a bathroom with the light turned off for a couple of minutes.
It works perfectly. She got the message very quickly (we use it when she's broken training and has gone in the house) and we haven't had to use it much since.
The way I potty trained my puppy which was 4 months old I put her in a big cage and at the back of the cage I put a cardboard box (the ones u get from the grocery store that has canned goods in them) in the box I put dirt from outside and the rest of the cage I put her toys, blanket etc. She would go to the bathroom on the dirt at night and during the day u rush her out after she has eaten. She then puts the two together knowing the dirt is where she suppose to go. I never had a accident. Remember to always praise her with treats, hugs, kisses and so on. It's just like being a mom, no rest till they are trained. You also have to wake up anytime at night if they whine and run them outdoors. Good luck