From any screen, touch and hold the Recent apps icon(lower-left; beneath the screen).
Tap the Multi window icon (upper-right corner of app window) to open an app in split screen view.
Recently used apps are displayed in the lower window.
Apps that support Multi window have the Multi window icon in their title bar.
If there aren't any recently used apps, or if you want to open a different app, tap App list.
Tap an app in the lower window to add it to the split screen view.