how to print a file in the background [RESOLVED]

Try this example . I don't have printer at home to test it though .

MSDN Help
VB Code:
Example
The following example prints the file that is specified through the command line to the default printer.
 
Note: The example assumes that each line fits within the page width.
 
Use the System.ComponentModel, System.Drawing, System.Drawing.Printing, System.IO, and System.Windows.Forms namespaces for this example.
 
Public Class PrintingExample
    Private printFont As Font
    Private streamToPrint As StreamReader
    Private Shared filePath As String
    
    Public Sub New()
        Printing()
    End Sub    
    
    ' The PrintPage event is raised for each page to be printed.
    Private Sub pd_PrintPage(sender As Object, ev As PrintPageEventArgs)
        Dim linesPerPage As Single = 0
        Dim yPos As Single = 0
        Dim count As Integer = 0
        Dim leftMargin As Single = ev.MarginBounds.Left
        Dim topMargin As Single = ev.MarginBounds.Top
        Dim line As String = Nothing
        
        ' Calculate the number of lines per page.
        linesPerPage = ev.MarginBounds.Height / printFont.GetHeight(ev.Graphics)
        
        ' Iterate over the file, printing each line.
        While count < linesPerPage
            line = streamToPrint.ReadLine()
            If line Is Nothing Then
                Exit While
            End If
            yPos = topMargin + count * printFont.GetHeight(ev.Graphics)
            ev.Graphics.DrawString(line, printFont, Brushes.Black, leftMargin, _
                yPos, New StringFormat())
            count += 1
        End While
        
        ' If more lines exist, print another page.
        If Not (line Is Nothing) Then
            ev.HasMorePages = True
        Else
            ev.HasMorePages = False
        End If
    End Sub
     
    ' Print the file.
    Public Sub Printing()
        Try
            streamToPrint = New StreamReader(filePath)
            Try
                printFont = New Font("Arial", 10)
                Dim pd As New PrintDocument()
                AddHandler pd.PrintPage, AddressOf pd_PrintPage
                ' Print the document.
                pd.Print()
            Finally
                streamToPrint.Close()
            End Try
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub 'Printing    
    
    ' This is the main entry point for the application.
    Public Shared Sub Main()
        Dim args() As String = System.Environment.GetCommandLineArgs()
        Dim sampleName As String = args(0)
        If args.Length <> 1 Then
            Console.WriteLine("Usage: " & sampleName & " <file path>")
            Return
        End If
        filePath = args(0)
    End Sub
End Class