Do not mistake witchcraft for Wicca!
Wicca is a religion very loosely based on some of the old traditions.
Witchcraft, is a "craft"; not a religion. There are many books about Wicca, and it can be learnt from reading.Witchcraft cannot be learnt from reading. It takes a personal, hands on, teacher; and it takes many years.This is why a real witch would be reluctant to teach. Most witches learnt from childhood.
And by the way, witches rarely, if ever, cast spells!
And just because somebody says they are a witch doesn't mean that they really are! Witchcraft means so many things, to so many people, that the truth gets lost!