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 select the options under the Contextualize tab above for resources concerning an author's life, literary history, and historical context.
T. S. Eliot manuscript page from The Waste Land (1922) from Transcriptions: a Digital Humanities Project on the Cultures of Information