Reading and Writing to another file

I am working on .net 4.0
In my organisation there are two file format
1)PNB and 2)ACE(need to select any one of the format to convert to respective format
if i select ACE means through file browser i have selected PNB which will convert to ACE after submitting the button
In PNB there are thousand character in one LINE which contain the data and i need to seperate and form a string and seperate this string by ,(comma) as delimiter.
I have seperate the characters to string but the problem is that the string which are formed i need to pickup from middle and then write


Following is my code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace PNB
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{

}

private void button1_Click(object sender, EventArgs e)
{
if (openFileDialog1.FileName == "")
{
MessageBox.Show("This is the Error", "Error");

} //if (openFileDialog1.FileName == "")

StreamWriter SW;
StreamReader SR;
string S;
string SingleLine = "";
string bn;
if (rbPNB.Checked == true) { bn = "PNB"; } else { bn = "Ace"; }
SR = File.OpenText(openFileDialog1.FileName);
SW = File.CreateText("D:\\PNB\\" + bn + "1.txt");



if (bn == "Ace")
{
int[] numbers = {15, 18, 26, 27, 44, 74, 79, 99, 104, 114, 120, 128, 129, 146, 149, 154,169, 179, 184, 190 ,196, 198, 199, 211, 221, 241, 246, 276, 316, 356, 396,436, 476, 493, 510, 527, 544, 561, 591, 607, 619, 629, 639, 648, 652, 908
};
int s = -1;
//int a, b, c;

S = SR.ReadLine();
while (S != null)
{
int n = numbers.Length;






SingleLine = "";
int i = 10;
while (i <= 39)
{
int a = numbers[i];
int p = numbers[i - 1] + 1;//start
int q = a - p + 1;//End

SingleLine = String.Concat(SingleLine,S.Substring(p,q));
SingleLine = String.Concat(SingleLine, ",");
//above logic will seperate char to string but i want to pick up characters present at this positions 114, 15, 27, 44, 44, 316, 356, 99, 74, 591 and form a string with seperate commas and this will form a line and this line i will write in ACE format which i have specified above
and this should be for all line by line

} // while (i <= 39)




}








//Console.WriteLine("Start\t"+b);
//Console.WriteLine("Length\n"+c);
}

//SW.WriteLine(S);
SR.Close();
SW.Close();

//S = SR.ReadLine();
}
//SR.Close();
//SW.Close();
MessageBox.Show("Done");
//S = SR.ReadLine();
//SingleLine = "";
/*
int n = numbers.Length;
for (int i = 0; i < n; i++)
{



if (i == 0)
{
s = -1;
int a = numbers[i];
int b = s + 1;
int c = a - b + 1;
//Console.WriteLine("Start:\t" + b);
//Console.WriteLine("End:\n" + c);
}
else
{
//int k = numbers[i - 1];
int a = numbers[i];
int p = numbers[i - 1] + 1;//start
int q = a - p + 1;//End
//Console.WriteLine("Start:\t" + p);
//Console.WriteLine("End:\n" + q);

if (i == 10 || i == 1)
{

SingleLine = string.Concat(SingleLine,S.Substring(p,q));

}

}







//Console.WriteLine("Start\t"+b);
//Console.WriteLine("Length\n"+c);
}

}



S = SR.ReadLine();
while (S != null)
{

SW.WriteLine(S);

S = SR.ReadLine();
}
SR.Close();
SW.Close();
MessageBox.Show ("Done");*/
}
}

private void button2_Click(object sender, EventArgs e)
{
while (openFileDialog1.FileName == "")
{
openFileDialog1.ShowDialog();
}


}

private void rbPNB_CheckedChanged(object sender, EventArgs e)
{

}

private void rbAce_CheckedChanged(object sender, EventArgs e)
{

}
}
}


//Can any one will help me for te same

Code:

---

string AceFormatString = "";
int[] AceFormatPoints = { 114, 15, 27, 44, 44, 316, 356, 99, 74, 591 };

foreach (int i in AceFormatPoints)
{
    if (i == 114)
        AceFormatString = line.Substring(i, 1);
    else
        AceFormatString += "," + line.Substring(i, 1);
}

---