Why is the white witch in Narnia evil?

To know whether she is evil you have to read the first book of the Chronicles of NArnia " The magician's nephew." In the book a boy named Digory, who is Proffesor Kirk in the lion the witch and the wardrobe, enters narnia for the first time with his friend Polly. They meet the Witch (Jadis) who goes back to the real world through magical rings. She's evil because she wants to conquer all the worlds and eventually kill the Pevensie kids. She's evil because in Prince Caspian she tries to fool Caspian and in the Voyage of the Dawn Treader she tries to fool Edmund. Luckily no one gets fooled or killed. The white witch is only seen in four books - The magicians nephew. the lion the with and the wardrobe , prince Caspian and the Voyage of the Dawn Treader. She want to control Narnia by killing the kids. Another witch is mentioned in the Silver Chair, but its not her! The order of the movies is different from the actual order of the books. C.S Lewis was awesome!! I am a super Narnia Fan and i am ready to answer any of the questions about it !!