You can use the coupon (bonus) at the check out page; after you click Discount on APP, there will be an option for you to select the available discount.
Note:
One order can only apply one discount.
Some items, such as Flash Sale goods and Some Electronics Goods, needed help using coupons. Also, there are restrictions on item categories.
Each Coupon has limitations for use. Please notice the minimum order amount, the validity time and using conditions at [Account] - [Coupon].