Hello Oti,
Windows phone push notification have two type of push which named as Toast and Tile Notification. In Tile notification, you can set the background image, title and backcontent as well. Please have at this tutorial, it will help you to understand the basic concept of integrating Tile notification for your windows app.
About you second query, please make sure your project namespace are correct to receive push notification. Because it seems like you have registered your device with sample application. To overcome on this issue, uninstall sample application and unsubscribe your device from dashboard. Register your device from your application and send push message again to see in your mobile app.
Thanks,
Himanshu Sharma