Example: How did the invention of the printing press affect the exchange of information in Europe?
Keywords: printing press, Europe, information exchange, invention
Related keywords: Gutenberg, moveable type, literacy, reading, books
Decide what information resource might be most useful; ask your teacher or a librarian for help
Check out the "About" page of online archives to figure out if it covers your topic.
Try out different combinations of your keywords to see which bring back the best results for your research. Record what works best in your research journal.