How to add content on the blank page

When all files are closed,the background will show. Now it just a logo and used as a background-image,if I want to add some HTML element on the blank page,what should I do?In other word ,how to add the content of the red circle below?

@Darya thank you for the discussion, the framework currently does not support the use-case by default, but it should be possible to extend the application-shell to add your content by attaching to the main panel. There was a pull-request in the past that attempted to add support for the feature (Draft: Add a watermark widget by alxflam · Pull Request #10901 · eclipse-theia/theia · GitHub) but it was abandoned and no one has picked it up since which can also help to get started.