Open the first 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 to open Split View
Adjust the divider in the middle to change the app sizes
To open a second app from the Home Screen, swipe up to go Home, then drag the app from the Home Screen into Split View
To switch one app, swipe down from the top of the app you want to replace and choose another app
To close Split View, drag the divider all the way to the left or right
To use Slide Over, drag an app from the Dock to the center of the screen instead of the edge