The Best Overloaded Method Match For 'System.Data.SqlClient.SqlCommand.SqlCommand Error

Hi,
I'm new to ASP.NET, and am currently looking into XML.
I'm trying to write XML using data from an SQL Server 2000 table.  But I seem to be getting the following error regarding the SQL Server connection:
Compiler Error Message: CS1502: The best overloaded method match for 'System.Data.SqlClient.SqlCommand.SqlCommand(string, System.Data.SqlClient.SqlConnection)' has some invalid arguments

Source Error:

Line 23: {
Line 24: SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
Line 25: mySqlDataAdapter.SelectCommand = new SqlCommand(queryString, connString);
Line 26: mySqlDataAdapter.Fill(myDataSet);
Line 27: return myDataSet;
Source File: c:InetpubwwwrootmappingcreateGeoRSSFile.aspx.cs    Line: 25
 This is my code:using System;
using System.Data;
using System.Data.SqlClient ;
using System.Configuration;
using System.Collections;
using System.Text;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;

public partial class createGeoRSSFile : System.Web.UI.Page
{
protected void Page_Load(object sender, DataSet myDataSet, EventArgs e)
{
string connString = "server=SQLSERV1;database=Historical_Statistics;UID=dbuser;PWD=Password";
string queryString = "SELECT Town, PostCode, Latitude, Longitude FROM UKPostCodes";

using (SqlConnection mySqlConnection = new SqlConnection(connString))
{
SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
mySqlDataAdapter.SelectCommand = new SqlCommand(queryString, connString);
mySqlDataAdapter.Fill(myDataSet);
return myDataSet;
}

// Create a new XmlTextWriter instance
XmlTextWriter writer = new XmlTextWriter(Response.OutputStream, Encoding.Unicode);

// Start writing!
writer.WriteStartDocument();
writer.WriteStartElement("item");

// Creating the <town> element
writer.WriteStartElement("town");
writer.WriteElementString("PostCode",myDataSet .Tables[1].Columns("PostCode"));
writer.WriteElementString("geo:lat",myDataSet.Tables[1].Columns("Latitude"));
writer.WriteElementString("geo:lon", myDataSet.Tables[1].Columns("Longitude"));
writer.WriteEndElement();

writer.WriteEndElement();
writer.WriteEndDocument();
writer.Flush();
writer.Close();

}
}What seems to be causing this error?Thanks.