now this is a pretty easy guide:
log into worldofwarcraft and type in .lookupobject temple doors
and choose one of them as your wall.
Then do .lookupobject gate
and find a good gate for your city.
Now you can find a good spot to start building your city such as in programmer's isle. Ok so now that you have your walls and gate built, you can do
.addgo 20824 (giant orc tower)
and build that in your city if you want, Once your city is finished,
go to navicat and open the area triggers folder and overwrite one of the coordinates to the coordinates of your city, you can just do .gps for that.
remember you need the x,y,z and orientation,
After thats done open your game objects table and find the entry id from the area trigger and then you can change the name of the portal to whatever you want.
then just do .addgo (the entry id) and your portal is all set.
Here is the cool city that i created: