Ok, to make it simple, lets start a basic fight between our heroes and some mooks. We use gaming stones to represent our characters and any npcs
each circle represents a zone. if you're in the same circle, you're in zone 0. one circle away, zone 1, etc. All the circles do is to allow for people to spread out across a battle and still make sense of some type of distance.
For instance, Balthazar the wizard, Ferny Green the changeling, and Father Simon have been cornered by some Red Court vampires. Since Father Simon likes to bring the power of God, he rushes in. Zone 0. Ferny holds back a ways and shoots his handgun at Zone 2. Balthazar being a Wizard, throws arcane bolts of power at the vamps from Zone 3.
Father Simon is holding his own, but a couple vamps get past him and rush Ferny. Now Father Simon is still Zone 0 and Ferny is in Zone 0 as well. Balthazar is still Zone 3 from Father Simon's mooks, but Zone 1 away from Ferny's mooks.
I hope that makes sense.
The Ritual Circle and the "bullseye" is more dressing than anything else since there technically isn't a Zone associated with scrying or REALLY long range rituals. I was just trying to fill in some dead space.
But who knows... DFRPG might have something...
Sorry if there was any confusion on that.
Oh, and one more thing. I used circles simply due to the fact that they are so prominent in the Dresden Files. But you could use anything to separate the zones. We tried using twizzlers once... that didn't work out.