I think I'm going to need bunches of feedback. I suffered through the setup with the following equipment:
REW (of course)
ThinkPad Edge I3 Windows 7
XLR male to XLR female Microphone Cable - 15 feet
Dayton Audio EMM-6 Electret Measurement Microphone
Behringer 302USB Premium 5 Input Mixer With Xenyx
My basic setup for the 302USB was both mic gains set to about 1/3rd. Line/USB set from: USB play to: Main Mix, gain set to almost 1/2. Main mix gain set to a little more than 1/3rd.
My wiring for the mic was using XLR male to to XLR female cable going into mic in. The USB cable ran from the computer to the 302USB and provided the interface and the power (this is why I set the Line/USB above to USB play. The main mix ran to my receiver using the main mix output.
I struggled with the sound card calibration. Below is a picture of my final setup:

I think the way I ended up getting it to work was to take the out of the phones on the 302USB to the Line in on the 302USB, but I tried so many configurations I'm not sure which one ended up working for me.:scratch:
I used the mic calibration from the download by serial number page for Dayton.
So I was all set. The first thing I was interested was trying to determine the background noise floor in the room. This should provide a boundary between what the speakers are doing and what is ambient in the room. (Paraphrased from a Dennis Erskine document). In order to determine the 1/3rd octave measurement I recorded the average FS db using the SPL Meter in REW with equipment on and no sound to be -48db. I then found that a 1/3 octave is a change in sound loudness level of -15.58db(
http://www.sengpielaudio.com/calculator-spl.htm), which resulted in a -63db FS pink noise. I produced the below 1/3rd octave full range RTA using -63db FS pink noise.

So my questions are:
Did I do it right? If not, what should I try?
What is the first charts I should be looking at to get a feel for how well the existing room treatments are working. My gut says I'm losing high frequency.
Do I need to attach some files? If so, what do you want?
Thanks,
Jim