Writing a basic XML file with C# (ELEMENT)

using System;
using System.Text;
using System.IO;

namespace login
{
/// <summary>
/// Summary description for Class1.
/// </summary>
class Class1
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
{
//
// TODO: Add code to start application here
//
string userid, pwd, conn;

Console.Write("Login Name: ");
userid = Console.ReadLine();
Console.Write("Password: ");
pwd = Console.ReadLine();

// one line per xml entry
//conn = "<userid>" + userid + "</userid> <pwd>" + pwd + "</pwd>";
http://Console.WriteLine("{0}",conn);

WriteFile("<connection>");

string timeStamp = "<timestamp>" + DateTime.Now + "</timestamp>";
Console.WriteLine("{0}",timeStamp);
WriteFile(timeStamp);

conn = "<userid>" + userid + "</userid>";
Console.WriteLine("{0}",conn);
WriteFile(conn);

conn = "<pwd>" + MyXOR(pwd) + "</pwd>";
Console.WriteLine("{0}",conn);
WriteFile(conn);

WriteFile("</connection>");
}

public static void WriteFile(string data)
{
// create a writer and open the file
TextWriter tw = new StreamWriter(@"conn.xml",true);
// write line of text to the file
tw.WriteLine(data);

// close the stream
tw.Close();
}

static string MyXOR (string data)
{
string key = "test";
string retValue = "";

int i = 0;
int x = 0;

int[] cipher = new int[data.Length];

x = 0;
for (i = 0; i < data.Length; i++)
{
http://Console.Write((char)((data[i] ^ key[x])));
retValue = retValue + (char)((data[i] ^ key[x]));
cipher[i] = (data[i] ^ key[x]);
x++;

if (x >= key.Length)
x = 0;
}

return retValue;
}


}
}