iOS: Add a widget to your home screen
1. Touch and hold the free space until the apps jiggle on the home screen.
2. Tap the Add button on the upper-left corner.
3. Look for the Countdown Time widget and tap to select it.
4. Choose from three widget sizes, then tap Add Widget.
5. Tap Done, or tap a space on the screen, and you are finished.
Visit the official Apple support to read more about adding a widget on an iPhone.