The general mythology teaches that pillars are named after the Dragon which created them.
People join pillars for a variety of reasons. Some simply attune to whichever pillar is close by, others attune to a pillar their family belongs to, or a pillar that they believe shares their ideals and beliefs about the world. It is not uncommon to feel "called" toward a certain pillar during adolescence or after a major life event.
The process of joining a pillar involves physically journeying to it and offering attunement, at which point the pillar will either accept or reject. If accepted, the follower forms a link with the pillar that allows him or her to channel Quasith (magical energy) to create supernatural effects.
All pillars are led by both a Sentinel and an Archon. Though the process is not fully understood, these leaders seem to somehow be chosen by the pillar itself, and all who are attuned to a pillar can "feel" when this happens within the pillar they are attuned to.
The Sentinel is seen as a defender/military commander, and is generally chosen based on combat prowess.
The Archon is seen as a political/spiritual leader, and is chosen for reasons that vary greatly from pillar to pillar. Should the Sentinel and the Archon ever be in conflict, the Archon's word is supreme.
Everyone in the party should be familiar with their own pillar, as well as a general knowledge of The First, Vormyll, Azzur, Losken, and Mercayen.
If your character has done a lot of traveling and/or reading, they will know about many of the other pillars on this map as well.