When you have a discount code you want to apply to your order you first need to add products to your cart.
Once you have added all your products to your cart, you need to proceed to secure checkout:
In the checkout you can find or insert the discount code when you select Show order summary:
Note that on a large screen device you will simply see the input field on the right side of your screen.
You can then add the discount code in the Gift certificate field and hit the Arrow button:
If your order is eligable for the specific code you will see the discount applied.
ILGM Customer Service