C#

WebBrowser Web = new WebBrowser();
string postdata = "ctl00_pass=1234";
System.Text.Encoding a = System.Text.Encoding.UTF8;
byte[] SendBytes = a.GetBytes(postdata);

Web.Navigate(WebBase + WebAddress, WebTitle, SendBytes, "Content-Type: application/x-www-form-urlencoded");
.

<form name="aspnetForm" method="post" action="default.aspx?key=5555" id="aspnetForm">

<input name="ctl00$pass" type="text" id="ctl00_pass" />

</form>
.

fileNot = textBox1.Text;
fileHid = textBox2.Text;
string[] lines = File.ReadAllLines(fileHid);
StreamWriter sw = new StreamWriter(outFile);
foreach (string line in lines)
{
    string oldhid = line.Substring(0, 11);
    string newhid = line.Substring(14, 11);
    StreamReader sr = new StreamReader(fileNot);
    string holdLine;
    while (!sr.EndOfStream)
    {
        holdLine = sr.ReadLine();
        string matchId = holdLine.Substring(0, 11);
        string noting = holdLine.Substring(11, 650).Trim();
        string dnot = holdLine.Substring(11, 2);
        if (oldhid == matchId && dnot != "D1")
        {
            sw.WriteLine(newhid + noting);
            break;
        }
    }
    sr.Close();
}
sw.Close();
swr.Close();