as stated Wicca and Witchcraft are different, but you could open a spiritual/witchy shop, sell spells/tarot readings online, teach classes, or try writing books on the subject. i would try and find a local pagan shop and try working their or at the very least speaking with someone who runs a witchy shop to understand what to expect.
reading your profile however i feel you have a lot to learn before diving into being a 'professional witch' read and practice more. it's nice to have a dream, but take the next couple years to gain more wisdom, look into studying things like business, finances, if you're interested in selling books a few writing classes wouldn't hurt. good luck to you.