Adding discount code to the cart screen can speed up your checkout conversion. You can do this by adding an introduction and the discount code to the shopping cart page. It will be displayed at the top of the page. By default, the cart has no custom text at the top.
In your eCom admin, go to Marketing.
Copy the discount code you want to add to your shopping cart screen. If none have been created yet, create a new one.
Select Back to Home.
Click on Content.
In the list on the Pages screen, select My Cart. If you can't find it, your cart may have a different name. Select the title of the page with Cart in the Page type column of the table.
Write an introduction to the promotion in the CONTENT field and paste the discount code.
For more information
About changing your shopping cart, click here.
About using the content text editor, click here.