Open an app
Swipe up slightly from the bottom to show the Dock
Touch and hold the second app in the Dock
Drag the app to the left or right edge of the screen
Release it when the split screen appears
Adjust the divider in the middle to change app size
To switch apps, swipe up and choose another app from the Dock
To close Split View, drag the divider all the way to one side
If needed, enable multitasking in Settings > Home Screen & Multitasking > Multitasking
Use an iPad model and app that support Split View