In the Variable & Property tabpage you will see all the Variable and Property elements that are used in the script. 

 

Adding a new Property to use the AppIcon:
  • If you right click on the page you will see the menu with the item "Add the icon property....."
  • Click on it
    AddPropertyMenuItem2
  • After you click on it you can select the Icon from the list.
    SelectAppIconInputDialog
  • Press Ok to create the property element.