A good starting place, encyclopedias and "Companions to Literature" can provide general information about an author's life, concerns, & social environment as well as some historical context for their work.
Information about an author's life and times, the society they worked in, and the sources they drew on in their work can all help provide context for understanding and writing about literature. Please use the following links for resources concerning an author's life, literary history, and historical context.
T. S. Eliot manuscript page from The Waste Land (1922) from from T.S. Eliot, The Waste Land: a Facsimile & Transcript of the Original Drafts, ed. Valerie Eliot, Faber & Faber (London: 1971)