Your questions aren't very specific, so here's some general advice on room measuring (and below that) room treatment:
All About SPL Meters
Room EQ Wizard, Windows and Linux and Mac OSX 10.4+, Freeware
ETF, Windows, $150
FuzzMeasure, Mac, $150
Using ETF explains how I use ETF, but the principles apply to all such programs.
Comparison of Ten Measuring Microphones
How to set up a room