A popup message can be added to your app to appear to app users upon first login. This is a great way to show off a Sponsor and welcome attendees to your app.
Once you have created the popup message navigate to App > Settings. From this page you can select your popup from the 'welcome popup' field. Click save.
The popup will appear upon first log in to your app. To remove it, change the welcome popup back to 'none' and save.