Help:Get New Content
From TrainzOnline
The Get New Content Option on the main menu contains the DLC available for purchase, as well as download player-made routes and sessions or upload your own. A Planet Auran account must be set in the Trainz settings to support this service.
Pressing the play icon on the bottom right corner will open up the in-game browser, offering a detailed description of the selected package and the way to acquire it.