how to set the values of sill,nugget,range in ordinary kriging?

Question

im work on temperature data ,and i want to interpolate the data to any location that i specify . my programming language is asp.net4 c#. i dont know how can i determine the sill,range,nugget for experimental variogram or theoratical variogram? i make the following code to calculate these variables in experimental variogram :

public void Calculate_EmpericalVari_nugget_sill_range()
{
  double H=0,VaiogramValue;
  int N = KnownPoints.Count;
  for (int j = 0; j < N; j++)//calculate the emperical variogram
  {
    for (int i = 0; i < N; i++)
    {
      H = AucledianDistance(KnownPoints[i].X, KnownPoints[i].Y, 
                            KnownPoints[j].X, KnownPoints[j].Y);
      VaiogramValue = 0.5 * Math.Pow((KnownPoints[i].Z - KnownPoints[j].Z), 2);
      Emper_Variogram[i][j] = VaiogramValue;

      if (H==0) nugget = VaiogramValue;
      if (sill < VaiogramValue)
      {
        sill = VaiogramValue;
        range = H;
      }
    }
  }    
}

I work according to the following that sill is the max value and range is the distance when i get the sill and nugget is the value at distance equal zero? does this right? and do they remain constants when i calculate the theoretical semivariogram