B4J Question jPOI - Excel change cells

Dim jo As JavaObject = Workbook1
jo.RunMethod("removeSheetAt", Array(<index of sheet here>)) '0 to remove the first one

Dim wb As PoiWorkbook
dim Sheet_SIPARIS As PoiSheet

    wb.InitializeExisting("Foldername","file name","")
    If wb.IsInitialized Then
    Sheet_SIPARIS=wb.GetSheet(0)
    Dim row As PoiRow
    For i=Sheet_SIPARIS.FirstRowNumber+1 To Sheet_SIPARIS.LastRowNumber
        row=Sheet_SIPARIS.CreateRow(i) ' this line delete line on selected sheet
    Next
end if
wb.save("Foldername","file name")
wb.Close

Dim wb As PoiWorkbook
dim Sheet_SIPARIS As PoiSheet

    wb.InitializeExisting("Foldername","file name","")
    If wb.IsInitialized Then
    Sheet_SIPARIS=wb.GetSheet(0)
    Dim row As PoiRow
   
        row=Sheet_SIPARIS.getRow(1) ' this line read line on selected sheet
    Dim poicells As PoiCell 
poicells= row.CreateCellString(0, DateTime.Date(datetime.now)) 'this line change volues on cell(1,0) 
end if
wb.save("Foldername","file name")
wb.Close