How to add images to a story board?(Launching screen)

I follow the following blog for creating IOS splash: https://docs.microsoft.com/en-us/xamarin/ios/app-fundamentals/images-icons/launch-screens?tabs=vsmac

I created a new launching screen file for my xamarin forms app, but can't see any option for adding an image for launching screen. Adding a screenshot of my current screen:

From where I can see the menu options for adding an image? I open it by double-clicking the file. When I run showing a blank white screen as the splash screen.

Also, I try to create the launching screen by adding all the images specified in the Assets.xcassets file, adding a screenshot of that:

Thanks in advance