To find books written about a specific play, Browse Alphabetically by Topic in the library's catalog, and type the name of the playwright (last name first) in the search box. For example, to find books about the plays of Christopher Marlowe, type "Marlowe, Christopher." Books about all aspects of Marlowe's works will now appear, organized by various subheadings under his name, which is the main heading. The heading "Marlowe, Christopher, 1564-1593. Doctor Faustus" will list the books that focus specifically on Doctor Faustus, but other headings (such as "Marlowe, Christopher, 1564-1593. Criticism and interpretation") will list books that provide extensive discussion of the play, too.
If you are looking for books about a more general topic, search in the library catalog and type words that occur to you to describe your topic. If the first terms you type do not give you the results you want, try typing in various ways of describing your topic. Then, once you find some books that look like what you want, click on the "Subjects" links that appear in the full records for those books. You will now probably find even more books on the same topic. (For example, if you type "Broadway musicals," you will find a few books about them. However, if you click on the link for the subject heading "Musicals -- History and criticism -- New York (State) -- New York," you will find more on the topic.)
Your results will probably include printed books that can be found in the library building, as well as electronic books that can be read online. You can tell which books are printed books because a location in the building is indicated as part of its record. E-books have no physical location indicated, and the words "Electronic" and "eBook" usually appear at the bottom of the record in your list of results. Click on the links above those words to read the book online.