Looking at the back 4 buttons. The button on the far right - press and hold power comes on. All digits come on. Two right hand digits show up to 99. These are the brightness, the two left digit are the temperature of the light. If you press the two buttons on the left, then the intensity goes up and down. Tap the second button from the right, press and the right two number flash. Use the two buttons on the left to change the value up and down. Colour temperature changes from 28 -60. Low value is warmer (more cream) , higher value is colder (more blue). That's all there is to it.