If you see a Shiny application running on the right side of this page, then Shiny is configured properly on your server and already running an example. Bravo! You can see this application on your server at /sample-apps/hello/.
If you see a gray box or an error message, then there's a bit more work to do to get Shiny running fully. You can continue with the installation instructions or use the Admin Guide for more information. If you're seeing an error message in the panel to the right, you can use it to help diagnose what may be wrong. If you think Shiny is installed and setup properly and things still aren't working, you can look in the Shiny Server log which may have more information about what's wrong. By default, the log is stored in /var/log/shiny-server.log.
If you're really stuck and you've read the relevant sections in the Admin Guide then please ask for help on our RStudio Community forum.