There are a number of ways you can start rearing guinea fowl.
1) Buy hatching eggs and incubate them or get a broody hen to incubate them.
2) Buy day old keets and raise them.
3) Buy guinea fowl poults from about 6 weeks old and raise them.
4) Buy sexed adult guinea fowl from 12 weeks onwards.
An excellent book is Guinea Fowl Past & Present by Michael Roberts, here is my review of the book.
Another great book is Gardening with Guineas by Jeanette S. Ferguson
Gardening with Guineas: A Step-By-Step Guide to Raising Guinea Fowl on a Small Scale
Click on this link for selected books from Amazon on guinea fowl.