The British were taxing everything at this point, and the colonists were getting very angry about it. This is what led to the famous Tea Party protest. Adams and the Observers club communicate with like-minded citizens who are interested in fighting back through the newspaper delivery. Johnny’s role in these chapters is that he delivers the papers and the coded messages.
In chapter 6, Adams and Mr. Lorne plan a meeting to deal with the arrival of the tea. Johnny is sent with a coded message, “Mr. So and So owes eight shillings for his newspaper,” and this lets people know that the Observers are meeting that night at eight.
Because of Johnny’s close association with John Adams and Paul Revere, he is on the inside scoop of revolutionary leanings. He hears things, and acts as a messenger. Thus he knows all about the Sons of Liberty and the Tea Party.