help me in the below program

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Collections;
using System .Collections.Generic ;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.IO;
using System.Data.OleDb;
using System.ComponentModel;

public partial class _Default : System.Web.UI.Page
{
    class Point  { double X, Y; }
    DataTable dt = new DataTable();
   
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnSubmit_Click(object sender, EventArgs e)
    {
        string connectionString = "";
        if (FileUpload1.HasFile)
        {
            string fileName = Path.GetFileName(FileUpload1.PostedFile.FileName);
            string fileExtension = Path.GetExtension(FileUpload1.PostedFile.FileName);
            string fileLocation = Server.MapPath("~/App_Data/" + fileName);
            FileUpload1.SaveAs(fileLocation);
            if (fileExtension == ".xls")
            {
                connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
            }
            else if (fileExtension == ".xlsx")
            {
                connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
            }
            OleDbConnection con = new OleDbConnection(connectionString);
            OleDbCommand cmd = new OleDbCommand();
            ArrayList List = new ArrayList();
            cmd.CommandType = System.Data.CommandType.Text;
            cmd.Connection = con;
            OleDbDataAdapter dAdapter = new OleDbDataAdapter(cmd);
            DataTable dtExcelRecords = new DataTable();
            con.Open();
            DataTable dtExcelSheetName = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
            string getExcelSheetName = dtExcelSheetName.Rows[0]["Table_Name"].ToString();
            cmd.CommandText = "SELECT * FROM [" + getExcelSheetName + "]";
            dAdapter.SelectCommand = cmd;
            dAdapter.Fill(dtExcelRecords);
            if (Session["dtInSession"] != null)
            {
                dt = (DataTable)Session["dtInSession"];
            }
            for (int i = 0; i < dtExcelRecords.Rows.Count; i++)
            {
                //if you want to get the string
                DataRow thisRow = (DataRow)dtExcelRecords.Rows[i];
               string X = Convert.ToString(thisRow["X"]);
              string  Y = Convert.ToString(thisRow["Y"]);
                //double Length = Convert.ToDouble(Y);
              double X1 = Convert.ToDouble(X);
              double Y1 = Convert.ToDouble(Y); 

                DataRow dr = dt.NewRow();
                polygonArea(X,Y);
            }

        }
    }
    //calculation
    private Double polygonArea(int X[],int Y[])
    {
        Double area = 0.0;
        int j = X.Length - 1;
   for (int i=0; i < X.Length; i++) 
   {
    area=area+(X[j]+X[i]*(Y[j]-Y[i])); 
           j=i;    
   }
   area =area/ 2;
        if (area < 0)
        area = area * -1;
    return area;
}

}