6 weeks is pretty early to have a Yorkie. I got Missy when she was 7.5 weeks old and we had problems with hypoglycemia. You may want to read up on it just to be safe. I had to use Nutrical.
What worked for us with potty training was setting up an ex-pen in the kitchen with a crate (door open) on one side, a pee pad on the other side, and food/water. I praised her each and every time she uses the pee pad (still do) and I would give her a tiny treat. Eventually once she really got the hang of it, I would start giving her more and more free reign of the house. I never punished her for going in the wrong spot. Just ignored it and cleaned it up, but I always praise he when she gets it right. She is consistantly using her pad at 18 weeks of age.
Good Luck!