Goto the file sharing area. I have uploaded many terrain examples which are simple. I don't change the names of the nodes. I do rename the surface layers, so don't let that throw you.
Basically you can do this also. Go in to the Lighting tab. Select the sunlight. An input area will open below this. Lower the suns altitude/angle to the horizon to about 12 degrees. Now move the slider of the sun position until the cross hair appears in the preview image on the top right of the program window. This is the sun location marker.
Now go to the Render tab. Un check the surfaces render option. Now the atmosphere and sun should render without the landscape.