Convert HTML to PDF and save in Folder (Disk) in Windows Forms using C# and VB.Net

I am working on windows based VB.Net 2010 application where i have to create and view Pdf file using VB.net 2010. For that i used the following code.

But when the program control reaches at the position System.Web.HttpContext.Current.Response.Clear() then a NullReferenceException is caught "Object reference not set to an instance of an object." I tried to solve it by creating object of that class. But when i try to create object of HttpContext then a error comes "Overload resolution failed because no accessible 'New' accepts this Number of arguments. Kindly solve it because it not getting solved by me for a long time.

  Imports System.IO
  Imports System.Net
  Imports System.Text
  Imports System.Data
  Imports iTextSharp.text
  Imports iTextSharp.text.pdf
  Imports iTextSharp.text.html.simpleparser
  Imports System.Web
  Imports System.Web.UI
  Imports System.Data.SqlClient
  Imports System.Configuration
  Imports System.Net.Mime.MediaTypeNames


  Private Sub exporttopdf(ByVal dt As DataTable) 
        Try

            ds = ObjTags.GetDischargeData(2)
            If (ds.Tables(0).Rows.Count > 0) Then
                dtTags = ds.Tables(0)

                If (ds.Tables(1).Rows.Count > 0) Then
                    dtTags = ds.Tables(1)
                    Label1.Text = "Grand Total : " + dtTags.Rows(0)(0).ToString()
                    tag = dtTags.Rows(0)(0).ToString()
                    startdate = dtTags.Rows(0)(1).ToString()
                    enddate = dtTags.Rows(0)(2).ToString()
                    currentdate = dtTags.Rows(0)(3).ToString()
                End If
            End If

            Using sw As New StringWriter()
                Using hw As New HtmlTextWriter(sw)
                    Dim companyName As String = "Vision Comptel"
                    Dim orderNo As Integer = 2303
                    Dim sb As New StringBuilder()
                    sb.Append("<table width='100%' cellspacing='0' cellpadding='2'>")
                    sb.Append("<tr><td align='center' style='background-color: #18B5F0' colspan = '2'><b>TEESTA BARRAGE WATER DISCHARGE REPORT</b></td></tr>")
                    sb.Append("<tr><td colspan = '2'></td></tr>")
                    sb.Append("<tr><td colspan = '2'><b>CURRENT DATE AND TIME :</b> ")
                    sb.Append(currentdate.ToString())
                    sb.Append("</td></tr>")
                    sb.Append("<tr><td><b>START DATE AND TIME : </b>")
                    sb.Append(startdate.ToString())
                    sb.Append("</td><td><b>END DATE AND TIME: </b>")
                    sb.Append(enddate.ToString())
                    sb.Append(" </td></tr>")
                    sb.Append("<tr><td colspan = '2'><b>Total Water Discharge <BR/> [ Gate-1 to Gate-44] (CUMEC) : :</b> ")
                    sb.Append(tag)
                    sb.Append("</td></tr>")
                    sb.Append("</table>")
                    sb.Append("<br />")
                    sb.Append("<table border = '1'>")
                    sb.Append("<tr>")
                    For Each column As DataColumn In dt.Columns
                        sb.Append("<th style = 'background-color: #D20B0C;color:#ffffff'>")
                        sb.Append(column.ColumnName)
                        sb.Append("</th>")
                    Next
                    sb.Append("</tr>")
                    For Each row As DataRow In dt.Rows
                        sb.Append("<tr>")
                        For Each column As DataColumn In dt.Columns
                            sb.Append("<td>")
                            sb.Append(row(column))
                            sb.Append("</td>")
                        Next
                        sb.Append("</tr>")
                    Next
                    sb.Append("</table>")
                    Dim sr As New StringReader(sb.ToString())

                    Dim pdfDoc As New Document(PageSize.A4, 10.0F, 10.0F, 10.0F, 0.0F)
                    Dim htmlparser As New HTMLWorker(pdfDoc)
                    Using memoryStream As New MemoryStream()
                        Dim writer As PdfWriter = PdfWriter.GetInstance(pdfDoc, memoryStream)
                        pdfDoc.Open()
                        htmlparser.Parse(sr)
                        pdfDoc.Close()
                        Dim bytes As Byte() = memoryStream.ToArray()
                        memoryStream.Close()
                        
                        System.Web.HttpContext.Current.Response.Clear()
                        System.Web.HttpContext.Current.Response.ContentType = "application/pdf"
                        System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=Employee.pdf")
                        System.Web.HttpContext.Current.Response.ContentType = "application/pdf"
                        System.Web.HttpContext.Current.Response.Buffer = True
                        System.Web.HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache)
                        System.Web.HttpContext.Current.Response.BinaryWrite(bytes)
                        System.Web.HttpContext.Current.Response.[End]()
                        System.Web.HttpContext.Current.Response.Close()
                    End Using
                End Using
            End Using
        Catch ex As Exception

        End Try
    End Sub