The vagina is only the tunnel that runs between the vaginal opening and the cervix - what is between the major labia is the "vulva." This is a lovely article that sets all the misconceptions about the female parts straight (but not necessarily heterosexual. ;p).

They also have an article that males will find useful! Innies & Outies: The Penis, Testes, and More

Scarleteen is a lovely, unbiased site that is my go-to on any sexual things I hear. They cover the sexes, but also the intersexed, the gender spectrum (no binary there!), and sexuality as well.