Ben1234:
What kind of values should R6 and R5 be? I am not sure how to calculate it. The LEDs will draw 320mA per hour and I was thinking of using a Transistor - PNP 60V 200mA (2N3906) - COM-00522 - SparkFun Electronics . I will need to cut the total current to 200mA.
The MOSFET should go between R4 and ground.
The wiper of the pot should connect directly to the gate of the MOSFET (with no resistor).
Now put a resistor R1 from +5V to one leg of the POT and another resistor R2 from the opposite leg of the pot to ground.
R1 should be about 20k, R2 should be about 5K.