Philips Hue Tunable white

[Karaffe]

How do I get it out that I can change the color temperature by a percentage value, either via the absolute color temperature 7,600 or via a 4-bit dimming step 3,007

with this script.
Can someone help me, I'm a complete novice 

Code:

function setBrightnessCT(Light_num,brightness,ct)
  if brightness == 0 then
    body_msg = '{"on":false}'
    response = sendToLight(lamp_id,body_msg)
    return response
  else
    brightness = math.floor((brightness / 1) + 0.5)
    brightness = math.floor((brightness * 2.54) + 0.5)
 
    ct = math.floor(1000000 / ct)
    ct = math.min(500, ct)
    ct = math.max(154, ct)

    --HTTP request send
    body_msg = '{"on":true,"bri":'..brightness..',"ct":'..ct..'}'
    return sendToLight(Light_num,body_msg)
  end
end