Display a full-width banner image at the top of your collection page by setting up the Full-Width Collection Banner Template.
Add the Collection Image
In your Shopify Admin, open Products, then Collections.
Locate the collection and click it to open the editor.
On the right side of the editor, select Add image below Collection image.
Upload your image.
Assign the Collection Template
Select banner from the Theme template selector.
In order to use the this template, the theme will need to be published. The templates you can select are limited to the templates available in your currently published theme. If you are unable to currently publish your theme, we have instructions on how to access unpublished templates here.
If you're using a different theme and want to add a banner image to a collection page, check out this article.