The three-minute video below, produced by Kealin McCabe, provides basic instructions for using a journal index.
Kealin is using the multidisciplinary journal index Academic Search Premier in the video, but remember that most journal indexes operate in essentially the same way.
Tip: Subject terms (sometimes called descriptors) are there for a reason. Use suggested subject terms, or subject terms that you find in database full entries, to revise your searches.