Every notification that's been sent to you via the app is saved inside your personal notification center. In case a notification was sent, but you haven't read it yet, you'll see a red sign in the upper right corner of the screen. To access notifications follow these steps:
- Tap on your icon at the top left corner when you are on the main page fo the app or the menu button when you are in a particular event.
- Tap on the "bell" button near your profile pic and view the notifications.
If you are an event organizer, check this article for the info on how to send push notifications.