SuperSearch is a great place to start for journal articles, books and almost everything else the library has, in one easy to use interface.
For searching with more focus and precision, try one of the databases recommended on this guide.
Databases can contain a combination of full text articles (ready to read online) and/or citation information about articles, book chapters, books, or other resources.
When searching, skimming items you come across in your results can be a key way to evaluate whether they will be a useful source for your writing. See UNC Chapel Hill's guide to skimming for tips.