It is called Vodun not - old slave magic

It can also be pronounced/spelled (Vodou, Vodoun, Vudu, or Vudun)
First if you are attempting on trying some voodoo remember it isn't a game. I'd take it serous.
Now as you know Voodoo traces back to African origins.
West African Vodou has its primary emphasis on the ancestors, with each family of spirits having its own specialized priest- and priestess hood which are often hereditary. In many African clans, deities might include Mami Wata, who are gods and goddesses of the waters; Legba, who in some clans is virile and young in contrast to the old man form he takes in Haiti and in many parts of Togo; Gu, ruling iron and smithcraft; Sakpata, who rules diseases; and many other spirits distinct in their own way to West Africa.
The word Voodoo is primarily used to describe the Afro-creole tradition of New Orleans, Vodou is used to describe the Haitian Vodou Tradition, while Vudon and Vodun and Vodoun are used to describe the deities honored in the Brazilian Jeje (Ewe) nation of Candomble as well as West African Vodoun, and in the African diaspora. Voodoo or Hoodoo also refer to African-American folk spirituality of the southeastern USA, with roots in West African traditional or "folk" spirituality.
An evil, imaginary religion, which we will call Voodoo. It has been created for Hollywood movies, complete with violence, bizarre rituals, etc. It does not exist in reality.
To learn more about voodoo you should read up somethings on the interent or vist a library/book store.
For books I would ask a clerk at a book store or check out the In New Age & Alternative Beliefs sections of stores.
A site i recommed: http://geocities.com/Athens/Delphi/5319/