Q. How do I become Wiccan?
A. Honestly, if you don't know this then should probably be doing more research before deciding to BE Wiccan. As with any other religion, you can call yourself a member if you have the same beliefs and follow the same practices.
Wicca is a specific religion and NOT simply a catch-all term for any Pagan beliefs. These days, there is a great deal of information available on Wicca via books and websites. Only through reading and research can you learn what it means to be Wiccan.
Many traditionalists feel that the only way to truly become Wiccan is to be initiated into an existing coven, and to be trained and guided by the people who have already learned. If you want to try a solitary Wiccan path, there are many books that take that specific approach, with the classic one being Solitary Wicca by Scott Cunningham.