how to draw rectangle over the image and save it in VB.Net

I have used below code to draw rectangle on the image but i an not able to save the image with the highlighted rectangle. only original image is saved not the image with rectangle.. please help me this..

`Private Sub PictureBox1_MouseDown(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
If e.Button = Windows.Forms.MouseButtons.Left Then
IsMouseDown = True
SelectedObjPoint = New Point(e.X, e.Y)
End If
End Sub

Private Sub PictureBox1_MouseMove(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove

If IsMouseDown = True Then
If e.X < SelectionBoxObj.X Then
SelectionBoxObj.X = e.X
SelectionBoxObj.Width = SelectedObjPoint.X - e.X
Else
SelectionBoxObj.X = SelectedObjPoint.X
SelectionBoxObj.Width = e.X - SelectedObjPoint.X

End If
If e.Y < SelectedObjPoint.Y Then
SelectionBoxObj.Y = e.Y
SelectionBoxObj.Height = SelectedObjPoint.Y - e.Y
Else
SelectionBoxObj.Y = SelectedObjPoint.Y
SelectionBoxObj.Height = e.Y - SelectedObjPoint.Y
End If
Me.Refresh()
End If

End Sub

Private Sub PictureBox1_MouseUp(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
IsMouseDown = False
End Sub

Private Sub PictureBox1_Paint(sender As Object, e As System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
If SelectionBoxObj.Width > 0 And SelectionBoxObj.Height > 0 Then
Dim oGradientBrush As Brush = New Drawing.Drawing2D.LinearGradientBrush(SelectionBoxObj.RectangleF, SelectionBoxObj.FillColor, SelectionBoxObj.FillColor, Drawing.Drawing2D.LinearGradientMode.Vertical)
e.Graphics.FillRectangle(oGradientBrush, SelectionBoxObj.RectangleF)

Dim TempPen = New Pen(SelectionBoxObj.BorderLineColor, SelectionBoxObj.BorderLineWidth)
TempPen.DashStyle = SelectionBoxObj.BorderLineType
e.Graphics.DrawRectangle(TempPen, SelectionBoxObj.RectangleF.X, SelectionBoxObj.RectangleF.Y, SelectionBoxObj.RectangleF.Width, SelectionBoxObj.RectangleF.Height)
End If
End Sub

Private Sub Highlight_Ok_Click(sender As Object, e As EventArgs) Handles Highlight_Ok.Click

Dim datestring As String = Date.Now.ToString("yyyyMMddmmss")
Dim path As String = "D:\capture screenshot temp"
Dim currentsavepath As String = String.Format("{0}\capture_{1}.png", path, datestring)

 PictureBox1.Image.Save(currentsavepath, Imaging.ImageFormat.Bmp)
End Sub`