The network is a type of tightly controlled centralised internet. Most people in citadels have access to look at the network but they cannot just post things on it. Ultimately controlled at a structural level by the king, each of the Houses connected to the network (most houses in the north and the tribes of the Lands of Shemka aren't) has a scribe. The scribe and his office censor and overlook anyone petitions them to have placed on the network. This could be anything from advertising that something is for sale to announcing a wedding. If they agree the scribes then post it.
The House and their scribe are responsible to the king for anything that gets posted in that houses name. The scribe is therefore a powerful position within each house. But the network is not just functional, it is full of entertainments and advertisements for entertainments. Recently the Principality of Barthena have been producing incredible dramatic spectacles and posting them online and the theatres in Crownhome also post performances.