1. We give every new customer a 10% OFF if total order up to $49, each person could ues once for this special welcome discount. Discount code:GIFT10. For some other discount like buy together our 3 binding product together you could get 5% OFF for total orders.2. If you're checking out on mobile, during checkout, you'll arrive at a screen where you can enter your billing and payment information. At the top of the screen, you will see "Show Order Summary" with a down arrow next to it. Shopify hasn't quite nailed this just yet, but you'll have to manually hit the down button to reveal the discount code field. Enter the code and you're good to go!