First off, pat yourself on the back. You are a proud owner of a Baopals coupon. That's cash money right there. So how do you turn those characters and digits into sweet sweet discounts? Easy.
On checkout, below your Total Price and above your Default Address, you will see the text "Apply Coupon/Promo Code". Clicking on the text will cause it to expand revealing a text entry box where you can enter your coupon code. Once you have correctly inputted your coupon code click the check mark to apply it. Your coupon value will be immediately applied and your Total Price will update reflecting the coupon discount.
If you get the message "The coupon code you entered is invalid" then that means the coupon you entered has either already been used, expired or was entered incorrectly.