Wicca is a modern religion which began in the 1940's based on the writings of Gerald Gardner. Although it is a modern religion, it is based on some of the practices of the pre-Christian religions of Europe. It is also composed of bits and pieces from Ceremonial Magic, Masonic rituals, folklore, and bits of British folk magic. It is a polytheistic religion, meaning Wiccans believe in the existence of many Gods and Goddesses, but in general Wiccans work with a Moon Goddess and the Horned Lord. Wicca does have very specific beliefs and practices that define the religion as being Wicca rather than something else. You can find a number of posts full of information about Wicca on this site at http://www.spellsofmagic.com/read_post.html?post=580909 There is more good information to be found at http://wicca.cnbeyer.com/wicca101/index.shtml
I'm curious as to why you think you might want to become Wiccan when you don't even know yet what Wicca is or what Wiccans believe. To my mind choosing a religion and a spiritual path involving the Divine is too serious and life-changing a decision to be made on a whim.
If you're thinking about making this change because you think you need to be Wiccan in order to do magic you are misinformed. There are many forms of magic, including traditional witchcraft, which do not require one to have any particular religious beliefs.