Charles, download a copy of Audacity:
http://audacity.sourceforge.net/download/
Use the "plot spectrum" feature in the "analyze" menu.
Algorithm: spectrum
Size: 16384
Function: Hanning Window
Axis: Log Frequency
OP, you can alter the bridge mass (and thus the top's resonance frequency) with bridge pins. Experiment with some brass pins. You may only need one or two.