The bashboard is where you can see the maps you are a participant of, the maps you are the owner of, and finally the characters you've created.

Maps I'm participating in

The first column is a list of maps you are a participant of. As a participant, by default you can modify combatants and zones. The map owner can lock the map, so all you would be able to do is view it.

My Maps

The second column is a list of maps you have created, and are there for the owner of. Usually this means you're the game master, and as such have special privileges. You can also create new maps here, and delete maps you no longer need.

My Characters

The third column is a list of characters you have created. A character is a shortcut to creating a combatant on a map. Here you can also add new characters and delete ones you no longer need.