How to read excel sheet data and add those data to database?

i have so far tried so many methods starting with OLEDB,ODBC and it worked but only offline but when i published my website it showed many errors and was to slow and then i shifted to NPOI a third party freeware tool and the code that i used is as follows :

protected void btnthirdparty_Click(object sender, EventArgs e)

        XSSFWorkbook wb;

        XSSFSheet sb;

        System.Data.DataTable dtnpoi = new System.Data.DataTable("Table");

        dtnpoi.Columns.Add("SheetNames");

        FileUpload1.SaveAs(HttpContext.Current.Server.MapPath(FileUpload1.FileName));

        string file = Server.MapPath(FileUpload1.FileName);

        using (var fs = new FileStream(file, FileMode.Open, FileAccess.Read))

            wb = new XSSFWorkbook(fs);

            for (int s = 0; s < wb.Count; s++)

                ddlsheets.Items.Add(wb.GetSheetAt(s).SheetName);

            for (int i = 0; i < wb.Count; i++)

                dtnpoi.Rows.Add((wb.GetSheetAt(i).SheetName));

            foreach (DataRow row in dtnpoi.Rows)

                String[] excelsheets = new String[dtnpoi.Rows.Count];

                int k = 0;

                excelsheets[k] = row["SheetNames"].ToString();

                string company = excelsheets[k].ToString();

                for (int j = 0; j < excelsheets[k].Length; j++)

                    ISheet sheet = wb.GetSheet(excelsheets[k]);

                    for (int rowsh = 0; rowsh < sheet.LastRowNum; rowsh++)

                        if (sheet.GetRow(rowsh) != null)


       //--------------------The Problem Is Here---------------------------------------//

                            DataRow rw = dt.Rows.Add(sheet.GetRow(rowsh).GetCell(rowsh).StringCellValue);

                            //ds.Tables[0]=null;

                            // = sheet.GetRow(rowsh).GetCell(rowsh).ToString();


                    for (int i = 0; i < dt.Rows.Count; i++)

                        DataRow rows = dt.Rows[i];

                        int coloum = dt.Columns.Count;

                        string[] colom = new string[coloum];


                        for (int m = 0; m < dt.Rows.Count; m++)

                            colom[m] = row[m].ToString();

                        db.USP_Insert_TestTable(company, colom[0], colom[1], colom[2], colom[3], colom[4], colom[5]);

                        company = "";

                k++;

    } 

i get the names of the sheet properly but the problem is after getting those sheet names 
i need to insert those sheet data to datatable so that i can save it to databasse but am unable to do so!! 
pls help me with that!!!