Brightness is the black level, you need a pluge pattern. The goal is to turn brightness up till you see below black, then turn it down till below black and reference black are the same.
Contrast you start at max, you need a visual contrast pattern. You want to see to 254, if you can see 254, check to see if the ramp discolors. Turn down contrast till you can see 254 and the ramp doesn't discolor.
Sharpness needs a specific crosshatch sharpness pattern. Then you turn sharpness up and down till you don't see any ringing on the pattern and the lines don't blur.
Backlight you can actually use the meter to set, but basically you want backlight bright enough for the ambient light but low enough to have dark blacks. typically that means 120-200cd/m in a room with ambient light.