If you only see one search box, look for an 'Advanced Search' or 'Add Field' link.
If you don't find enough by searching for information about the Lacks family, search for the broader concepts of paying research participants and of informed consent.
JSTOR is a big repository of scholarly articles. Many of the articles found here are from journals on ethics, culture, or society, and it has some science journals.
ABI/INFORM has news stories, public health sources, and business sources. It's helpful here to search for more than just the Henrietta Lacks name to remove at least some of the book reviews from the results.
Academic Search Complete has information about both popular and scholarly articles on a variety of topics and includes full text for many of them. It's a good place to get a few articles on a topic, especially if you are just getting started.