ASP.NET C# messagebox library

using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.IO;
using System;
using System.Text;




public partial class BackUp : System.Web.UI.Page
{
    SqlConnection con;
    SqlCommand cmd;
    SqlDataReader dread;


    protected void Button2_Click(object sender, EventArgs e)
    {
        if (File.Exists(@"C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Backup\PatientHistory.bak"))
        {
                      
            if (MessageBox.Show(@"Do you want to replace it?", "Back", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
               File.Delete(@"C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Backup\PatientHistory.bak");
            }
            

    }

}

}