What a precious little biter
Seriously though, she's a puppy and teething. Best way to help with the biting issue, is when she bites, say a stern "no bite" (not yelling but official-like

). Then stick a toy or chewie in her mouth that is acceptable and say good bite. She has to chew - you just need to teach her what is ok to chew and PRAISE HER LIKE CRAZY when she has the right thing in her mouth.
All dogs - especially Yorkies - crave praise and love so it's the best teaching tool there is