To apply a promo code on Petitcouture.com, you will need to follow a few simple steps during the checkout process. Once you have selected your items and are ready to finalize your purchase, navigate to the shopping cart or checkout page. On this page, you should find a designated area labeled "Promo Code" or "Discount Code." Enter your promo code in the provided field, ensuring that you input it exactly as it appears, since these codes can be case-sensitive. After entering the code, you will typically need to click a button to apply it. The total amount should then update to reflect the discount associated with your promo code. If the code is valid, the discount will be applied to your order. If you encounter any issues, it may be helpful to check the terms and conditions associated with the promo code or verify that it is still valid. Always be sure to review your order total before completing the purchase.