Enter in the author's name (Wilbur, Richard) to bring up biographical articles.
Contemporary Authors contains biographical and bibliographical information on Authors from the Contemporary Authors reference series.
The Scribner Writers Series has a biographical entry for Richard Wilbur. Click "Writers A-Z" and find his entry in the "W" section.
Credo is an excellent collection of reference sources (Encyclopedias, Dictionaries, etc). This entry on Wilbur from the Encyclopedia of American Poetry looks especially helpful, but there are many other sources as well.