How do I perform a more targeted search?
Choose Advanced Search from below the search button:

On the next screen, choose what part of the book record (known as the Search Index) you want to search from the first dropdown menu. This could be title, author, subject, or something else (although those are the most commonly used). You can add a second index/term combination by using the next line down, and so on, adding more if you need.
The Operator defaults to AND, which limits your search by only finding records with all of your terms. You can change the Operator to OR, which will expand your search to find any of your terms. NOT excludes whatever index/term combination you put after it.

In addition to Author, Title, and Subject, you will see Author Phrase, Title Phrase, and Subject Phrase. The "Phrase" part means that it searches for all the words you enter in the search bar. This is a narrower search. Without using the "Phrase" version, it searches for any of the terms. This is a broader search.