I'm not sure i understand. The wall wart i have plugs straight into the barrel jack of the arduino. How would i get another wire from it?
The shield Vin pin is wired to the barrel jack's positive terminal (through a series polarity protection diode) so it's avalible for your use as a 'raw' 9vdc in your case using that 9v power module you showed. But keep in mind that your servo may still draw more current then the 9vdc module might be able to supply and in any event you can't draw more then 1 amp from the Vin pin because of the polarity protection diode which is rated for 1 amp maximum current.
Servos have motors in them, motors tend to draw lots of current depending on the mechanical load placed on them, so planning proper power management for servo(s) is not a slam dunk easy task sometimes.