Excel - How to make read Only?

'Excel
                Dim oXL As Excel.Application
                Dim oWB As Excel.Workbook
                Dim oSheet As Excel.Worksheet
                Dim oRange As Excel.Range

                'StartExcelandgetApplicationobject.
                oXL =NewExcel.Application

                ' Set some properties
                oXL.Visible = False
                oXL.DisplayAlerts = False

                'Get a new workbook.
                oWB = oXL.Workbooks.Add

                oSheet = oWB.Worksheets(2)' Assuming there is > 1 sheet in the Workbook, get Sheet 2
                oSheet.Activate() 'Activate the Worksheet

                ' Get the active sheet
                oSheet = DirectCast(oWB.ActiveSheet, Excel.Worksheet)
                oSheet.Name = "Detay"

                'Style
                Dim style AsExcel.Style= oSheet.Application.ActiveWorkbook.Styles.Add("NewStyle")
                style.Font.Name="Verdana"
                style.Font.Size=12
                style.Font.Color=System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Black)
                style.Interior.Pattern=Excel.XlPattern.xlPatternSolid
                style.Font.Bold=True
                style.Interior.Color=System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Orange)

                'Headers
                oSheet.Range("A" + row_num.ToString + "").Value = "SNO"
                oSheet.Range("B" + row_num.ToString + "").Value = "ADISOYADI"
                'oSheet.Range("C"+ row_num.ToString+"").Value="NOKTAADI"
                oSheet.Range("C"+ row_num.ToString+"").Value="FIRMA"
                oSheet.Range("D"+ row_num.ToString+"").Value="BÖLÜM"
                oSheet.Range("E"+ row_num.ToString+"").Value="TARIH"
                oSheet.Range("F"+ row_num.ToString+"").Value="ÇIKISSAATI"
                oSheet.Range("G"+ row_num.ToString+"").Value="GIRISSAATI"
                oSheet.Range("A"+ row_num.ToString+":G"+ row_num.ToString+"").Font.Bold=True
                oSheet.Range("A"+ row_num.ToString+":G"+ row_num.ToString+"").Style= style

                row_num = row_num +1

                'Calculate
                Calculate(row_num, oSheet, period, time1, time2, date1, date2, ekstra)

                'Resize the columns
                oRange = oSheet.Range(oSheet.Cells(1,1), _
                          oSheet.Cells(100,7))
                oRange.EntireColumn.AutoFit()

                ' Save the sheet and close
                oSheet = Nothing
                oRange = Nothing
                oWB.SaveAs("c:\GirisCikis\Giris-Çikis(" + date1 + " - " + date2 + ").xlsx")

                oWB.Close()
                oWB = Nothing
                oXL.Quit()