Applying a discount code is usually a simple process during the checkout stage. When you're reviewing your cart, there’s typically a field labeled "Promo Code" or "Discount Code" where you can enter the code. After typing or pasting it in, click "Apply" or a similar button. The discount should then be reflected in your order total. If it doesn't work, double-check for typos, expired codes, or restrictions like product exclusions or minimum order amounts.