Craftnames are names given or chosen by a witch (yes boys are witches too, we're not genderized). Craftnames were created centuries ago, to keep the true identity of the witch themselves a secret. This was back in a time when witchcraft was a crime, punishable by death...Now, craftnames have become traditional with many branches of Paganism.
Keep in mind that these names are just for fun, if you really are looking for a craftname, ask a good friend to make one up for you, they know you best. My true craftname is Vywien, so i use it online as well, you could do the samething.