Buenas Necesito adaptar este cogido que encontré aquí mismo el cual me sirve para realizar gráfico de torta el tema es que se realizo en ASP.NET, loge adapatar en parte el a codigo a mi proyecto pero tengo un error el response.outputstream no entiendo par que se usa y no se como adaptarlo a vb.net
aqui el codigo

Public Class Page
   Private Sub Page_Load(ByVal sender As
        System.Object, ByVal e As
        System.EventArgs) Handles MyBase.Load Dim sql As New MySql

       Dim ds As DataSet = New DataSet()
       Dim Dt As System.Data.DataTable

       Dt = sql.LEER("SELECT Nombre, SUM(Venta) FROM sucursales GROUP BY meses ")

       
       Dim bc As gTorta = New gTorta()
       bc.Render(ds, Response.OutputStream)

Public Class gTorta
   Public Sub Render(ByVal chartData As
        DataSet, ByVal target As Stream)
       Dim dt As DataTable = chartData.Tables(0)

       'Se crea un nuevo grafico y se configura
       Dim bm As Bitmap = New Bitmap(400, 400)
       Dim g As Graphics = Graphics.FromImage(bm)
       Call g.Clear(Color.White) 'Pongo el fondo el blanco
       Call g.DrawString("Texto", New Font("arial", 20), Brushes.Black, 5, 3) 'Aquí pueden ingresar un texto que quieran
       Dim curAngle As Single = 0
       Dim totalAngle As Single = 0
       Dim i As Integer = 0
       Dim sumData As Single = 0
       Dim dr As DataRow
       For Each dr In dt.Rows
           sumData += Convert.ToSingle(dr(1))
       Next dr
       For i = 0 To dt.Rows.Count - 1
           curAngle = Convert.ToSingle(dt.Rows(i)(1)) / sumData * 360
           Call g.FillPie(New SolidBrush(ColorIm(i)), 100, 65, 200, 200, totalAngle,
                curAngle)
           Call g.DrawPie(Pens.Black, 100, 65, 200, 200, totalAngle, curAngle)
           totalAngle += curAngle
       Next i

       Dim rectY As Integer = 300
       Dim textY As Integer = 300
       Dim percent As Single = 0
       For i = 0 To dt.Rows.Count - 1
           g.FillRectangle(New SolidBrush(ColorIm(i)), 100, rectY, 20, 10)
           percent = Convert.ToSingle(dt.Rows(i)(1)) / sumData * 100
           g.DrawString(dt.Rows(i)(0).ToString() + " (" +
                percent.ToString("0") + "%)", New Font("Tahoma", 10), Brushes.Black, 130, textY)
           rectY = rectY + 20
           textY = textY + 20
       Next i

       bm.Save(target, ImageFormat.Gif)
       g.Dispose()
       bm.Dispose()

bueno espero su respuesta
aquí el enlace desde donde lo saque http://www.elguille.info/colabora/puntoNET/adripulvi_graficotorta.htm
gracias