T.S.
There are some great books at the library, the librarian can help you out there. I never actually had "the talk" with any of my kids, a boy and two girls. Rather it was over time, as questions came up. I kept it simple and age appropriate. For example when a young child asks where do babies come from they don't really need (or want) the whole biological description.
The American Girl book "The Care and Keeping of You" is a good one for girls in pre or early puberty.