With cboFunctions.Items
       .Clear()
       .Add("Befehl 1")
       .Add("Befehl 2")
       .Add("Befehl 3")
   End With

     Private Sub cboFunctions_SelectedIndexChanged _
     (ByVal sender As System.Object, ByVal e As System.EventArgs) _
     Handles cboFunctions.SelectedIndexChanged
 
        'Der gewählte Index
        Dim bef_ind As Integer = cboFunctions.SelectedIndex
        'Der gewählte Text
        MessageBox.Show(CType(cboFunctions.SelectedItem, String))
 
        If bef_ind = 0 then 
         'usw.

    Private Sub Button1_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles Button1.Click
 
        If tboUserName.Text.Trim <> String.Empty Or _
           tboPassWord.Text.Trim <> String.Empty Then
 
            Dim mytext As String = _
            tboUserName.Text.Trim & " " & tboPassWord.Text.Trim
 
            'auszuführender Code
 
        End If
    End Sub