You can launch recently used apps directly into Multi window view:
1-Tap the Recent apps key.
2-Recently used apps that support Multi window have a Multi window icon in the title bar. Tap the Multi window icon in the title bar to launch the application in Multi window view.
3-Other recently used apps that support Multi window appear below the launched app. Tap the app icon to add it to the Multi window view.
Note: Only applications that support Multi window have the Multi window icon.
Note sure if it is same to phone, but give it a try. I find it from pressing left bottom button, lll the 3 vertical bars button. Choose the app you want to do split screen. See my screenshot.
