The main search box on the library homepage will allow you to search for books or articles (plus more). It's a great place to start when you have a few keywords in mind and are just getting started with your research.
Search the catalog for books, manuscripts, journal titles, musical scores, etc. To see only materials online use the filter to the left and select "Online" as opposed to "In the library."
Search Articles+ by keyword when you are looking for articles on a particular topic, or by article title when you are doing known-item searching.