When customers have Gift Card codes, they can use them when checkout an order.
On the Website:
Customers can choose to use credit or Gift Card by ticking Use Gift Card to checkout checkbox. Then the system shows a box where Customers can enter gift codes. Besides, they can use gift codes they added to the list on Gift Card management page.
After Customers click on Apply Gift Card button, the Grand Total will be updated as below:
Customers can choose to use Gift Card code and enter the amount of money on the checkout page same as on Shopping Cart page.