This first image shows how you adjust the output voltage. You push the button above the number to raise the digit and the button below it to lower it. Including the fine adjustment potentiometer on the right this provides you with 5 significant figures of control.
The second image shows the current control dial. This model has the Option 14 ten turn current control installed. It allows very fine precision control of the output current, theoretically with a resolution down to around 1mA.
This last image shows the rest of the features on the front. The power switch, a switch that switches the meter between volts and amps, and lastly the overvoltage limit.