EDIT. Looks like this information is unnessecary before i even posted it ;p
And i just started today, so i doubt you're behind ;>
Well, the server territories are divided between European and American, and you can switch which set you'd rather use, although it's limited to 5 times. ;0
When you choose which set you want to use, then you can access the district servers for that territory and, whenever in a town, change between the different ones on that territory from a drop-down menu, kinda just different instances of the same place so it doesn't get too crowded. ;o
Also, you can always visit the international district instances without changing territories which contain anyone who chooses to use them- regardless the server set. ;>
To change which server set you use, when you log in just click "edit account" in the bottom left, then change territory. ;0
PICTURES :O
It's too late for witty captions ;<