You can enter your discount code in the shopping cart under Discount Code. Keep in mind that every discount code has its own terms and conditions that must be met for the discount to be valid on your order.
After entering the discount code and clicking Apply, you will either see a success message or an error message. In case the order doesn't meet the requirements of the discount code, it will indicate which requirements still need to be met.
After the discount code has been successfully processed, the discounted amount will be deducted from the total invoice amount.