Hm what kind of Voodoo dedication ritual ? Ancestral , feeding the Lwa, Mambo trance ....the list goes on , You will have to be slightly more specific.
Also African Voodoo ( as religion ) can be practiced only by initiated / dedicated ( perhaps whis was the rite You were asking about ? ) . There are other systems You can practice without mandatory decication rite , such as Creole Voodoo , New Orleans Voodoo and few other.
To add a spell here You must be Council member, unless You are a member of "Spellcasters" group , as there are all members are automatically set to council position.
In such case You hit the spellbook tab, then the add spell tab