Launchers setting has a list of launcher names that reside in game folder. Change or add new ones if you need. First valid executable will be launched when user clicks Launch button.
Publishing the updater executable
Right-click Updater project in Visual Studio and select Publish...
You will be greeted with the Publish Wizard. All the steps are pretty self-explanatory. Specify a URL where your updater files will be hosted. This is how it will autoupdate. I put my updater files into launcher folder on my server. So can you.
After all of the steps completed, press Finish and navigate to publish folder in the project's directory. This is what you will need to upload to your server with your favorite FTP client.