As of version 3.2.0., this section has been removed as it has been deemed a negative visitor experience because it pushes your blog content further down the page. Your newsletter call-to-action should appear either in the sidebar, the post content, or below the content.
The Before Header widget area is styled for a Genesis eNews widget, which is used to get your readers to subscribe to your newsletter. You can drag and drop a Genesis eNews Extended widget from the available widgets area into the Before Header widget area and then see this information for how to get your newsletter subscription service setup with Genesis eNews.