Take a look at the Baltimore write-up, and the City-Building sheet from the back of Your Story.
Stuff I'd include:
1)Town's Mortal Overview- (setting, general history, major events, etc.)
2)History: (describe the past supernatural activity if any)
3)Present Day: Mortal & Supernatural stuff nowadays (include factions, context to the books (is the Vampire War going on? post-Changes? Paranet? Period piece?)
4)Dramatis Personae: Write up as many NPCs as you deem necessary. Include Aspects. Maybe include "photos".
5)PC write-ups: Optional section, but recommended. Write up 1.5-2x as many PCs as you think you'll need to give your players choices, and build them for your city. Your players COULD use them, or make their own.
6)Mundane Locations: Write up as many locations as appropriate. Include aspects, and PHOTOS if possible.
7)Supernatural Locations: See 5.
8)Probable Events- Give the GM some likely things to happen in this town, in order to get the game going (ie plot hooks). For example, an alderman is killed by a vampire. A Warden is passing though. Etc.
9)Mods, GM notes (any modifications you've made to DFRPG for this game. For example, I'm playing a game where "Chest Deep" has 31 skills points rather than 30, but at least one must be put in a new skill, Chess.) Also, the GM should leave his notes in here- leave some blank paper.
10)Sample Adventure (give a scenario, and how PCs might act in them- see the casefiles released for what I mean.)
Disclaimer: This is DIFFERENT from a plot-driven campaign. For example, the games I run are typically hyper-extended "one-shots" with a specific goal in mind. A writeup of this kind should have a much longer combined Probable Events/Sample Adventure section.