To use a promo code on Little Passports, follow these steps: First, select the items you wish to purchase on the Little Passports website. Once you have browsed the site and chosen your items, proceed to the checkout page. On the checkout page, you will see a field where you can enter your coupon code. Enter the promo code in this field and proceed with the checkout process. The discount associated with the promo code should now be applied to your purchase. Remember, each promo code may have its own terms and conditions, so make sure to read them before applying the code.