Multimeter - quick tutorial?

[mainstreetexile]

I have a pretty basic Craftsman multimeter but I don't have much experience with it. I need to test an effects box cable power cable for polarity. The cable plugs into a PedalPower2 -- the other end, that will go to the effects pedal, is two bare wires right now. I need to attach that to the plug that comes with a Klon so I can power the Klon with the PedalPower. So, can anyone give me a quick rundown on how I should set the multimeter to check polarity and how to do that so I can tell, for sure, which of the two wires is + and which one is negative?

[zaguitart]

Set to volts DC, red lead (+) and black lead (-).
Attach a red lead to a wire, attach black lead to other wire.
If the meter reads negative (-) volts, then the black lead is attached to the positive (+) wire.
If the meter reads positve volts, then the red lead is attached to the positve (+) wire.

[mainstreetexile]

thanks -- I'll let you know when I get this worked out.