1. Start RailWorks in the launcher.
2a. In the first menu screen, select Editor.
2b. In the next menu screen, select a route to place your locomotive in from the left panel. Then select Edit Route from the right panel.
3. Click on the Scenario Tools icon in the upper left flyout menu. Click Yes in the Warning message that follows.
4. Click on the Scenario Markers icon in the middle left flyout menu.
5. The text of the menu changes. Select Free Roam Scenario Marker from the menu.
6. A Scenario Marker appears. Click on it and adjust its location to suit.
7. Double-click on the Scenario Marker. The gray edge of a flyout menu appears on the right side of the display.
Open the new menu and replace the words <supply name> in the Scenario Name edit box with a suitable scenario name of your choosing.
8. Click on the big orange Drive arrow at the lower right of the screen. Click Yes in the Save? message.
At this point it is recommended that you quit RailWorks and re-launch it. Your new scenario should be ready for further editing.