Looks like I need a tutorial added….but to setup a banner or image, upload the image to your media library and copy the File URL then use a text widget with HTML to load the image:

Or if the jetpack widget works for you, use that. But to publish it on a select page, use the widget visibility feature from Jetpack to publish this widget into the banner widget position and select on what pages you want it to show.
https://www.styledthemes.com/preferential-setup/279-show-a-widget-on-select-pages-only