If you've been searching the WWW for some sort of definitive Witchcraft bible, guess what? you're out of luck. That is one of the joys of Witchcraft and Wicca, there are no strict guidelines or must-do's to abide by in order to follow this path. The variety of beliefs and practices amongst pagans can often be quite confusing to someone wanting a simple, straight up 'This is how you do it' explanation. So, you have my apologies if that's what you were hoping for.
Paganism, is an earth-based spirituality, or religion if you'd prefer. If you consider Paganism to be a really large umbrella under which Witchcraft, Wicca and many other varied spiritual paths have formed, you'll get a better idea of why there are so many differences. For example not all Witches consider themselves to be Wiccans, and not all consider themselves Pagans as their methods and beliefs can differ greatly. Confused yet?