numbers. ok. first, 30mA is the max value, probably. it will burn the paint on your ceiling at that current.
for a superbright led, you can run at say 5mA andblind the neighbours, attract low flying planes, etc. at 0.5mA, or 500uA, you will have a status indicator instead.
so, V+ = 9V; Vf = 3V2; I(led) = 500uA, R3 = xR.
V+ - Vf = V(R3). VR3 is the voltage we want to "drop". 9 - 3.2 = 5.8. R = V(R3) / I(led) (Mr Ohm). xR = 5.8 / 0.0005 = 11,600 or 11k6. you can use 12k or 10k, and probably not tell the difference.
the led brightness varies with the led current. you must ALWAYS use a current limit resistor with leds (unless they are audio clipping). you can do all the calculations each time if you like, or just use something between 4k7 and 22k for a 9V supply, scale between depending if you want to indicate or room lighting.
you can and should look up the part number and see the manuf datasheet, for parts you know and parts you don't. there will be surprises.