Purchase a bar code scanner. These are easy to find and relatively inexpensive. Double-check that the scanner you choose is compatible with the operating system on the computer you intend to use with the scanner.
Download the appropriate drivers for your scanner. These are necessary to make it work with your computer. The driver may not be included with the scanner. There are many free software websites where drivers are available. Match the driver with the brand and model of your scanner.
Locate the ISBN on your book. This is not the same as the bar code, although it looks similar. According to ISBN.org, the letters "ISBN" appear before the code, and it consists of 10 digits, unlike the standard bar code used by retailers which has 12 digits. You may also see an ISBN-13, which will begin with the numbers 97, and have 13 digits.
Hold the scanner so that the glass slit through which the laser shines is aimed at the ISBN.
Allow a second or two for the scanner to read the number. If it does not read the ISBN, gently move the scanner up and down over the ISBN until it registers with a little beep.