Next to the call number, the Davidson Library Catalog tells you which general area of the library a book is located. Given this information, look at the below chart to determine where your book is located. The Davidson Library Catalog tells us that This Brutal World is located in the Main Library Stacks. As This Brutal World has a Library of Congress call number, the book is located near the center of the ground floor.
Once you've determined this, you can search the below floorpans to pinpoint where your book is located. Using the charts, you can determine that This Brutal World is located somewhere inside the below red circle.
In the red circle, look for the bookcase that contains the NA prefix. Scan this bookshelf until you find books in the NA682 range. Then, scan the NA682 range of books until you find the books labeled NA682.B7. One of the books marked with the call number NA682.B7 should be your book; This Brutal World.
Note: For an example of using call numbers to browse library shelves, look at this guide (created by the University of Las Vegas).