You can check your credit balance any time by clicking on «Credit notes» in your account menu. You can use credit to pay for your next shopping spree. The next time you’re in the middle of ordering something and click on «Payment», your credit will be taken off the total.
I forgot to use my credit note when I was ordering!
Don’t worry. You can still redeem your credit note after you’ve placed your order. Go to «My orders» in your account menu to find the order you want to edit.