Well, I've got this now:

VB Code:
  1. Public Class Form1
  2.  
  3.     Dim Stoppen
  4.  
  5.     Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
  6.         'create the mail message
  7.         Dim mail As New System.Net.Mail.MailMessage()
  8.         Dim Van, Naar, Onderwerp, Tekst, Slaap, Host, Cc, Bijlage_1
  9.         Van = TextBox1.Text
  10.         Naar = TextBox2.Text
  11.         Onderwerp = TextBox3.Text
  12.         Tekst = TextBox4.Text
  13.         Slaap = TextBox6.Text
  14.         Host = TextBox7.Text
  15.         Cc = TextBox8.Text
  16.         Dim myFile As String = OpenFileDialog1.FileName 'Assign selected filename to var
  17.         If OpenFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
  18.             MessageBox.Show(myFile)   'It gives full path
  19.         End If
  20.  
  21.         'set the addresses
  22.         mail.From = New System.Net.Mail.MailAddress(Van)
  23.         mail.To.Add(Naar)
  24.  
  25.         If CheckBox1.Checked Then
  26.             mail.CC.Add(Cc)
  27.         End If
  28.  
  29.         'set the content
  30.         mail.Subject = Onderwerp
  31.         mail.Body = Tekst
  32.  
  33.         mail.Attachments.Add(myFile)
  34.  
  35.         'send the message
  36.         Dim smtp As New System.Net.Mail.SmtpClient(Host)
  37.  
  38.         '//CURSOR
  39.         Me.Cursor = Cursors.WaitCursor
  40.  
  41.                 smtp.Send(mail)
  42.  
  43.         Me.Cursor = Cursors.Default
  44.         pBar1.Visible = False
  45.         MsgBox("Operatie geslaagd!")
  46.  
  47.     End Sub
  48. End Class

But:
Error 1 Value of type 'String' cannot be converted to 'System.Net.Mail.Attachment'. E:\Documents and Settings\The King\Mijn Documenten\Visual Studio 2005\Projects\Mail\Mail\Form1.vb 52 30 Mail
Wich is here:
VB Code:
  1. mail.Attachments.Add(myFile)

How can I solve that?