How do I get all of my code in start function

I got the score text . How would I do the countdown timer code ?

So I leave countdown timer text like this :
Or How countdown timer code approach ?

Countdown Timer Script

using UnityEngine; using UnityEngine.UI;

public class $$anonymous$$yClock : $$anonymous$$onoBehaviour { public int $$anonymous$$inutes = 0; public int Seconds = 0;

  private Text    m_text;
  private float   m_leftTime;
 
  private void Awake()
  {
      m_text = GetComponent<Text>();
      m_leftTime = GetInitialTime();
  }
 
  private void Update()
  {
      if (m_leftTime > 0f)
      {
          //  Update countdown clock
          m_leftTime -= Time.deltaTime;
          $$anonymous$$inutes = GetLeft$$anonymous$$inutes();
          Seconds = GetLeftSeconds();
 
          //  Show current clock
          if (m_leftTime > 0f)
          {
              m_text.text = "Time : " + $$anonymous$$inutes + ":" + Seconds.ToString("00");
          }
          else
          {
              //  The countdown clock has finished
              m_text.text = "Time : 0:00";
          }
      }
  }
 
  private float GetInitialTime()
  {
      return $$anonymous$$inutes * 60f + Seconds;
  }
 
  private int GetLeft$$anonymous$$inutes()
  {
      return $$anonymous$$athf.FloorToInt(m_leftTime / 60f);
  }
 
  private int GetLeftSeconds()
  {
      return $$anonymous$$athf.FloorToInt(m_leftTime % 60f);
  }

}

I almost forgot where the scenes go ?