first of all, in magick and witchcraft, there is no black or white. It is both because nature is both.
Paganism does not mean a single religion, it is a umbrella-term for all non Jewish/Christian/Islam religions. Wicca, Druidism, Hinduism, Shintoism, Buddhism, Taoism, Native American religions, Shamanism, and witchcraft practices and all native/folk religions are all pagan religions.
Wicca is a neopagan religion, all Wiccans are pagans but not all pagans are Wiccans. Not all Wiccans practice witchcraft and not all witches are Wiccans. Wicca is a religion, witchcraft is a practice. You can be a Christian, a Jew, a Buddhist etc and practice witchcraft.
Just like nobody is born a Christian, nobody is born a witch or a pagan. Anyone can practice witchcraft, all you have to do is learn and study. Please note that real magick does not mean that you yell gibbrish and things happen, its really spiritual, and there are no spells that make you fly, float, change hair color etc. Spells are a form of prayer. Potions are basically herbal medicine and concoctions, to make a cup of herbal tea with magickal intent is making a potion.
You should read some books and do some studying first before casting any spells.
Books I recommend:
"Wicca: A Guide for the Solitary Practitioner" by Scott Cunningham
"Buckland's Complete Book of Witchcraft" By Raymond Buckland
"A Witches Bible" by Janet and Stewart Farrar
"Witchcraft Today"by Gerald Gradner
These books should give you some basic understanding of real witchcraft.