Hi and Welcome to YT! We all feel for you, as we have all been there. At 12 weeks, your puppy will not be housebroken as their bladders are too small, and they are too young to fully understand. You will find a lot of useful info here:
http://www.yorkietalk.com/forums/for...ysprune=-1&f=6
or simply do a search located in the blue bar at the top of the page. Lots of info is provided, maybe too much, but just weed through it as best you can.
Good luck, and don't get mad at your pup, it takes time..........
We're glad you're here, enjoy your baby, it will come.........