Sellers can upload a store banner and post a store announcement:
Store Announcement - The store announcement will be displayed underneath the store header and will be dismissable. You can set the text font and background colors through your Store Settings. Your announcement should be limited to 80 characters.
Store Banner - The banner will be displayed in the Shop tab under All Items, Newest Items, and Wanted List (on top of the item information). Unlike the store announcement, the store banner will not be dismissable. Your banner should be limited to 100 characters.