I won't even get into the spell casting stuff, except to tell you that you can't 'cast a spell' on anyone. No one can.
I do not believe in Wicca or witchcraft or spells personally but I can tell you that in many non-Western cultures, there have been age old cultural/religious traditions involving practices akin to spell casting. i.e. placing curses or charms on people/places
Who figured this out? When did they figure it out? 25 years ago? Do you really want to go though life believing something that someone made up 25 years ago? Why did it take thousands of years for this one person to discover this great mystery, 25 years ago? Again, I really need to know who this brilliant person is. Is it the person who wrote your book? I wonder how much money she has made off the book.
True plenty of people/groups make money off religion. Just look at how wealthy many established churches are. But who is one to dismiss out of hand religious beliefs of others since these beliefs are necessarily spiritual in nature and can neither be proved or disproved? Plenty of people believe the Bible to be literally the word of God and that the world was created in 7 days. Was that something made up thousands of years ago? Who knows?
AdrenalynKittie, since you're quite young I hope you'll be exploring all different kinds of religions before deciding if one, or any of them is right for you.
ETA: I know nothing about the history of Wicca, but "witches" seem to have existed in history or folklore for centuries and are not a recent creation.