You start designing a railroad in the Layout window. The window has tow types of layers, "Track" and "Terrain". Designing is easy, just drag items from the Layout window and drop them on the layout. There are alsosome structures, buildings, trees etc, that can dragged from the Structure window. You can also create heights, even mountains, hollows or ponds in the Terrain layer.
Layout window
You can select layer type by the popup menu on the window.
Layout type menu