Also, if you really want to measurements, check out Room EQ Wizard. It is free and works very well. You will have to invest in a decent microphone ($70-100).
Edit to add one more thing. A "flat" response may not be what you want. And you will never see a completely flat line on any graph...
It is pointless measuring from 1 foot. Your room colors the sound dramatically. Measurements should be taken from your primary listening position (and not with phone).
Try Audyssey and see how you like it. There's a very old guide in my signature that should be good enough to get you started...