I’m still a bit confused about HOW the agents managed to communicate with and recruit each other?

I understand that they communicated and coordinated via some online message board, but how did multiple agents know to visit that same board, how did they know what language to post in that would make it identifiable to other agents, how did other agents know that said instructions were from other valid agents, how did they then ‘persuade’ an agent to do the job, etc.?

It seems to me that the agents must at least have some inherent mechanism for communicating in the field, as it were.