When you land on the application, you can either create a new map and edit the pre existing layout, or load a map_config.xml that you created and continue modifying it.
You can drag stations to move them accross the map.
You can also click a station to open its menu.
From there you can either click the top button to remove the station or the one on the right to create an interchange, after clicking on this button, click another station to link them together.
To unselect, just click a blank area on the map.
Add station : Use this button to add a station to a line, you can input the line right under the button.
Add line : Use this button to add a new line.
Export : Use this button to export the map to a format readable by the railway simulator, an exported map can also be loaded back into the editor.