if you would like to start out i suggest picking a path and doing research. you can research in wiccan or paganism, or follow no religion at all. witchcraft is completely secular, meaning apart from religion. you may want to look into paths such as green witchcraft, chaos, hedge, etc. http://www.kitchenwiccan.com/pagan-wiccan/types-of-witches/ is a nice simple over view of these things.
Also, learn about meditation and grounding and how to deal with your chakras. there are many articles about those on this site. These things are the most important before casting spells. You may want to focus at on chakra at a time untill they are all strong before you begin. Begin with easy spells, and if you are looking on this site be sure to know what is fake and what is real. Vampire spells and things of that nature are fake.
Nowadays is easy to get yourself some good information regarding many of the schools of thought and practices. Ancient and neo progressive ocultism. You tube, the local library and forums are interesting places to find examples of different practices.