Coupon codes or merchandise credit codes can be added to the "promo code” field at the cart, or in the checkout. Simply check the box "I have a promo code" and enter the code into the field and click Apply. 

Additionally, codes can be added in the Payment section of the Checkout. Simply check the box "I have a product voucher, or promo code" and enter the code into the field and click Apply. 

Please note that only one code can be applied per order.