+5V ----- Potentiometer----GND
|
\(the middle leg)
------------Analog 0
That should give you an input voltage on the Analog 0 between 0 and 5V. The analogRead returns a value between 0 and 1023. Use a potentiometer with at least 10K, 100K would be fine.
Yes, The PWM control varies between 0 (0% on) and 255 (100% on)