if your asking how to make model railway scenery? Simply be creative, there’s so many things you can use, for example if your wanting to do rolling hills, tunnels cuttings etc you can use polystyrene foam, this is light weight and easy to cut and glue in place. additioanlly card formers and rolled up newspapers covered in plaster bandage work just as well.
For other bits of scenery there’s plenty of different products available to create water features like rivers and canals, there’s also many building kits you can make and modify for buildings and other structures. There really is an endless list of things you can use.