Open the app you want to use in Split View
From the Dock, drag the second app to the right or left edge of the screen
Release when you see the Split View divider
If Split View doesn’t appear, open the second app from the Dock and then drag it to the side of the screen
To adjust the split, drag the divider left or right
To exit Split View, drag the divider all the way to one side
Alternatively, tap and hold the app’s multitasking button and select Full Screen