Well to start you need to understand the code written in the route. to help with that process, go
here to the BveStation Wiki page to understand the different parts of the route and to other links to help code the route that you want to build. Make sure you have RouteViewer from
here and unzip the files and place them in your OpenBVE directory. You will use Routeviewer to help you see the route and the changes you make to the route file without opening OpenBVE.