Add your store banner on your 'Store' settings page on the very top: https://merchantshowroom.com/vendor-dashboard/settings/store/ .
Make sure that the image is large enough and clear enough. We recommend a size 845x422 px. Please make sure that the image is related to your company's dealings.
Quality image is required for your store to be activated. If you do not have an image, we will use a stock image at our discretion.
This is a sample store banner with information pulled from your store's settings.