To use Coupon Code in Grasscity shopping, you only need to do the following three steps: 1. Log in or create a new account on grasscity.com. Select the Grasscity products you like and add them to the shopping cart; 2. Check the product you want to purchase at Grasscity; 3. Place the order, click on the Grasscity Coupon Code you got on the checkout page. Select the Grasscity Promo Code you want to use and just complete the payment.