Only mayors and above participate in D&SS. Anyone that has a settlement/county/duchy/kingdom to select will get to do so during this event. The kingdoms have been chosen. We're still waiting on the world maps to pick the rest.
After the event, which runs a total of 4 weeks (in Elyria, this is actually 1 week + X months delay + 3 weeks :D), there is a dutch auction period in which anyone can participate, if they wish to purchase a mayor/count/duke title and select an available domain or settlement. Basically, picking from whatever remains.
Hopefully, you can now find salvation from your state of confusion through this nugget of enlightenment.