Wicca is an earth based religion, one that is often misunderstood. As an alternate name for wiccan is witch, most seem to think that wiccans are evil or "worship the devil". This isn't true. In fact, most wiccans don't believe in the devil, as the devil is a Christian concept. And a second fact is that the wiccan rede states "An it harm none, do what ye will". In others words, just don't hurt anyone.
Wiccans believe in a goddess and god, with the goddess usually being the higher of the two, though some only worship the goddess. They recognize nature as being important, and it is often used in their spells and rituals. Some give nature the same reverence as the goddess.
Now back to the stereotype of witches being evil and doing "black magick". Wiccans don't do that. It all falls back onto the harm none rule. Plus whatever magick they do, good or bad, comes back at them three-fold, or three times as bad (Or good) as they sent out. So it's not only a religious "law", but it's also just good for the caster.