To apply a promo code to an order at CoastalContacts.com, customers should first browse the website and select their desired products. Once an item is added to the shopping cart, they can proceed to checkout. During the checkout process, there will be a designated field labeled "promo code" or "discount code." Customers should enter their valid promo code into this field exactly as it appears, ensuring there are no typos or extra spaces. After entering the code, it is important to click on the "apply" button to ensure the discount is processed. The updated order total will reflect any applicable savings. If the promo code does not work, customers should verify its validity and any specific terms associated with it. For more detailed guidance or specific inquiries regarding promo codes, customers may check the CoastalContacts.com website for additional resources or contact information.