Go to the Barnes & Noble website, and select the Gift Card option from the menu at the top. Under the Help heading, click Check your balance.
On the next screen, find the two information fields. Type your gift card number, without spaces, into the first box.
Find the four-digit gift card PIN on the back of the card. The PIN may be obscured with a sticker that needs to be peeled or scraped off. Enter the PIN, and click Check Balance.