You can run an application by clicking its application icon in a File Manager window. For example, you can run Image Viewer by clicking the file SDTimage in the folder /var/dt/appconfig/appmanager/user-hostname-0/Desktop_Apps/ where user-hostname-0 is a folder specific to your user ID.
If an application uses data files, it may be configured so that the application can be started from File Manager by clicking one of its data files. For example, double-clicking a bitmap file (a file whose name ends with .bm) runs Icon Editor.
For instructions on running applications from File Manager see "Executing an Action for a File or Folder".