Here you can create and manage your coupons. They can either have percental or a direct money value. If you use percental values, you just choose a value from 1 till 100%, else just set the money you want to give discount (No signs!). You can also limit coupon usage (e.g. Set that the coupon is only usable once or twice etc.). You can also set how long a coupon should be valid.
Per booking only ONE coupon code can be used!