One way to do this is by enabling split screen mode. We've developed an app to let you do this even if the apps you're using don't natively support split screen.
The app is called Good Lock 2018, and can be accessed through the Galaxy Apps Store. After installing it, open it and locate the feature "MultiStar", then install that as well. Check that the Good Lock 2018 app shows a green checkmark next to the MultiStar feature, then select it from the list to access the options. You should see an option called "Enable multi window to all apps." under the section "Multi window+". Toggle this on, and then restart your device.
After following these steps, you should be able to use any app in split screen. Hope this helps!
