iOS’ Notification Center
You can access the Notification Center by swiping from the top to the bottom over the screen. There you can activate CalenGoo’s Today Widget (requires iOS 8 or newer) to get a quick overview of your upcoming events:
To activate CalenGoo’s Today Widget just open the Notification Center, tap "Today" at the top and then "Edit" at the bottom. Search CalenGoo in the list and tap the green "+" button to make it visible. If you like you can also change the position e.g. to move it to the top.
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If you cannot find CalenGoo as an option in that screen, then start the "Settings" app, open "Notifications > CalenGoo" and turn "Show in Notification Center" on:
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Afterward CalenGoo should appear as an option in the notification center so that you can add it to your Today screen.