[op25-dev] waterfall

Ok I know I asked this before but im still stuck, why when I launch op25_25.PY I just get the waterfall app, im using the black rtl sdr how do I tell it to tune o a frequency? Where could I find the op25.grc file and just run op25 in gnu radio companion? Yea I know, I suck, I ask alot of dumb questions , but im tryin! Cant wait for the live cd to come out!