The first step in drafting your program notes is to confirm the composer's name (with correct spelling), birth and death dates, and the authoritative name of the work in its original language. Additional identifiers such as key, opus number, and year of composition are also important and will help you search for more information.
Open New Grove and search for your composer's name. At the start of the entry you will see the full spelling of their name, with any variants, and the date and place of their birth and death.
For "bigger names" you will see the article contents in the left side navigation, and a link to a works list near the end. Here you can find specifics about the work you are performing. You may find notes on when the work was composed, and in some cases, the date and place of the premiere.
Some contemporary composers, and older, lesser-known composers, may not be listed in New Grove. In this case, you'll want to search the SearchWorks catalog for composer biographies. Official websites for living composers are also a good source for reliable factual information.