There is an extremely large number of biographies and books about Winston Churchill. Anyone interested to learn more about him will find no shortage of information on the bookshelves as well as online.
Yet another way in which we might understand the contributions and significance of Winston Churchill is to examine primary sources and documents relating to his life and times.
A good place to start is the collection of primary sources in very beautiful Churchill: The Treasures of Winston Churchill, the Greatest Briton, published in association with W.S.C.Churchill Heritage.