What games do you want to show. Currently there is TANE-Std & TRS19 showing. Usually they appear here once you have registered your serial No. in the game although some of the older ones (eg. 2009) and a few Steam ones may require the intervention of the help desk. You can put stuff into your signature too if desired.
After you log in with your Trainz ID in whatever game it is you’re trying to get to show up (TRS19, TRS22, T:ANE), it should automatically appear. If it isn’t, contact the help desk.
If it does not accept your serial numbers or you do not have serial numbers than only the helpdesk can help you. Serial numbers are not transferable so you can't register used copies of these games.