Add products to cart: Select all product options of the items and then select the "Add to Cart" or "Buy Now" option.
View your cart: Click the cart icon if you select "Add To Cart" option before. This will take you to Checkout Detail page. If you select "Buy Now" option, the site immediatly move to Checkout Detail page.
Enter the coupon code: At Checkout Detail Page, click at the line text "Have a Coupon or Gift card? Click here to enter your coupon code" and then you will see a text box for apply coupon code. This is where you'll need to enter your code.
Apply the Discount: Enter your discount code into the field. Verify the code for accuracy and then click the "Apply coupon" button.