Its the study of magic and tarot cards and reading Ora's select which apply to u also look at these http://www.google.com/search?q=define%3Awicca&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7ACAW_enUS356US357
By far, the most reasonable apologists for your religion are the folks at time rift.net, but be careful, you might not like a lot of what they have to say.
Just say it's a polytheistic religion based on Chakras, the four elements, and elevating yourself to a higher level of consciousness. Also explain that it's not evil, and that it takes a lot of focus and meditation. You can also explain astral projection, spiritual communication with other-worldly beings, and nature spirits. Hope that helps.
Repeat after me; "It is a polytheistic religion that, depending on the sub-group you're in, often believes in a God and Goddess. Alot like Buddhism, Wicca is a religion with a deep spiritual connection to nature. That's about it." there you go.
I had to explain my religion to my 86 year old Grandmother. I told her that I was a pagan and that is someone who worships nature, believes that "God" is also female and that I believed in the beauty and balance of all things. I told her if she wanted to know more or understand more, that I would answer her questions as best I could. Her first question was: "Do you have a leader?" and I said that we do not. There are men who created certain denominations of Paganism, such as Gerald Gardner and Victor Anderson, but that we do not worship THEM. (She was afraid I was in a cult). She also asked if we had a book like the Bible and I said no. She asked if I worshiped the devil and I said no, as I don't even believe in him, and how can you worship something that you don't believe in?
The biggest thing that made her feel better was to watch me, and listen, and in seeing that I didn't do anything that worried her, she felt better.
It's just a matter of being well educated to exactly what Wicca is and being ready for questions about it.