You can input any/all coupon codes at the checkout screen.
At the checkout screen, where it lists the items and total price, there is a box marked "discount". Enter your coupon code there and hit the apply button to redeem your coupon code.
It is important to redeem your coupon code before hitting the checkout button, as we are unable to retroactively add in coupon codes once your order has been made.
Furthermore, our coupon codes unfortunately cannot be stacked, meaning only one coupon code can be used per order.