Does using the catalog confuse you?
Don't worry, you can figure it out.
Remember: use the keywords of your question or subject.
Also: SUBJECT is going to find you books ABOUT the topic, the entire book will be about Shakespeare.
KEYWORDS: is only looking in the catalog for records that have Shakespeare somewhere, whether it's works by William Shakespeare, someone named George Shakespeare who wrote a book on motorcycles, or biographies about William Shakespeare, playwright and poet, etc.