To check the app inbox you navigate to the profile icon which is the green circle with a person inside it, at the bottom right of your screen and select 'Inbox.'
You also access your notifications centre through the profile icon. You then select 'Settings' and can adjust all WordGo notifications from here. You may also need to access the notifications centre from within your device settings to make sure everything is also turned on here.
Here's a quick video walking you through how to do this.