You do not need to past it. The route "Mountain Valley RR Trainz" is showing up for people to get into. You only need to send the link to people you want to join you but may not know the route that is yours.
Currently the process is to copy paste the link (send it via email/chat program etc to the other person). Then then copy / paste into Developer > Open Url.
Could there not of been a more intuitive/fluid way of doing this? seems like an after thought really, the connecting to MPS needs to be streamlined really to call it an actual release?
The intuitive way right now is "type in the name of the route while in-game". The url option is a future feature for inviting people external to the game to come and join you (not fully implemented as yet).