Here's a link to at least get you started. Every subject on the left side is clickable and you'll get info and pictures.
Dog Breeding and Canine Reproduction by Debbie Jensen. Dog Breeding and Whelping guide for dog breeders.
If you're totally inexperienced, you may want to consider taking her to the vet at whelping time. Yorkies are not a breed where you can let nature take its course. Assistance and intervention is necessary.