Your theme must support app blocks (Shopify Online Store 2.0)
Collection Page Banner: A banner that can be displayed somewhere on your collection page for the collections that are attached to the discount offer.
Product Page Banner: A banner that can be displayed somewhere on your product page for the products that are attached to the discount offer.
Global Banner: A banner that can be displayed somewhere on almost any other page on your storefront such as the home page. This will only show for offers that apply to the entire store.
Editing Messaging For An Offer
When you are editing an offer, scroll down to the "App Block Messaging" section to find these three options where you can enter custom messaging for that offer. Messages will only be displayed if an offer is active and within any other parameters that may apply such as, start date, end date, and customer tags.
Customizing Your Theme
Click "Online Store" in your Shopify admin dashboard and then select "Customize" for your current theme.
Select the template you would like to edit. This example will be selecting the default collection template to display the discount banner.
Add the "Discount Banner" listed under "Apps" anywhere you would like on the page by clicking "Add block" if you are adding to an existing section, or "Add Section" if you are adding it as a new section.
Adjust the color and font size using the settings on the right side of the page when the discount banner is selected.