To create a promo code, go to Site Settings → Payment Systems → Promo Codes.
Enter a discount code. It should be a combination of letters and numbers, up to 12 characters in total. Set a discount type: percentage or a flat amount (the currency of your promo code will match the currency used in your online store), set the number of promotional codes you'd like to offer (if the restriction is not necessary, leave the field empty or set it to 0), and set an expiration date.
Save the changes.
Go to the page with the shopping cart and create a "Promo code" input field in the Content panel of the shopping cart block. The new field will appear in the order form.
The discount code applies only to the total price of all goods. It does not apply to delivery charges or any extras.
You can create up to 500 promo codes.
The promo code is not case sensitive – if you set the code as "HELLO" (all caps), "hello" (lower case) will work just as well.