Talk to the Gateguard (the one that cast signet)
you see a list of options (signet, spend CP, supply quest..)
you will see "expeditionary force"(sp?) , then he gives you each region's name and level cap,
as I heard, you can do it as a full alliance for best results ..
Hmmm, last week sandoria was busy, we controlled almost all and forced the other 2 to team up ;) GO SANDY