Please forgive my ignorance, but once I have the meter, what exactly do I do?
There's no ignorance to be forgiven, aside perhaps from my own :-)
Thinking about it a little further, I believe that to get meaningful readings with a battery powered DMM you MIGHT have to provide it with an AC ground reference. That could be done by connecting a piece of ordinary hookup wire between the screw on the wall plate of an AC outlet, and the capacitor lead to which the DMM's "common" terminal is connected. I'll describe the procedure as if that wire is necessary, although I'm not completely certain that it will be necessary.
What you would do is as follows:
Set the meter to read AC voltage, on a fairly sensitive scale that would resolve a millivolt or so. If the meter has a "LoZ" (low input impedance) provision, disable it. Connect the meter's com (common) input lead (or whatever the equivalent nomenclature may be on the particular meter) to one end of the capacitor. Connect the wire from the wall plate screw to that same point, perhaps holding it in place with an alligator clip that may be provided with the meter, or that may be attached to the end of its lead. Connect the other lead from the meter to the other end of the capacitor.
Put your hand on the capacitor, and see if you get a reading. If not, drape the AC power cord of some powered up electrical device across the capacitor, and see if that gives you a reading. Note the value of the reading.
Remove the three connections from the capacitor. Connect the com lead of the meter and the wire from the wall plate screw to the opposite end of the capacitor than the end they were originally connected to. Connect the other lead of the meter to the opposite end of the meter than it was originally connected to. Repeat the voltage measurement.
The end of the capacitor that was connected to the com lead and the ground wire when the lower of the two measurements occurred is connected to the capacitor's outer foil.
Best,
-- Al
