Push notifications are enabled by default as part of the iOS. All you need to do is choose which apps you want to get notifications from and what type of alerts they send. Here's how to do that:
- Tap the Settings app to open it
- Tap Notifications
- On this screen, you'll see all the apps installed on your phone that support push. Settings for each app are managed separately, so find an app you want to configure and tap it
- The first option is to Allow Notifications from this app. If you want notifications, move the slider to On/green. If not, move it to Off/white and go on to another app.