C# อยากทราบวิธีอ่าน File Excel แล้วให้มันเก็บค่าที่ได้ไว้ใน Array

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using MsExcel = Microsoft.Office.Interop.Excel;

namespace MsExcelInterop
{
    class ExcelManagement : IDisposable
    {
        private MsExcel.Application _xlApp;
        private MsExcel.Workbook _xlBook;

        public ExcelManagement (string FilePath)
        {
            _xlApp = new MsExcel.Application();
            _xlApp.Visible = false;
            _xlApp.ScreenUpdating = false;
            _xlApp.DisplayAlerts = false;

            _xlBook = _xlApp.Workbooks.Open(FilePath, 0, true, 5, Type.Missing, Type.Missing, true, MsExcel.XlPlatform.xlWindows, "\\t", false, false, 0, true, true, Type.Missing);
        }

        public List<object[,]> GetSheetData()
        {
            List<object[,]> sheetData = new List<object[,]>();

            foreach (MsExcel.Worksheet xlSheet in _xlBook.Sheets)
            {
               MsExcel.Range xlRange = xlSheet.UsedRange;
               object[,] valueArray = (object[,])xlRange.get_Value(MsExcel.XlRangeValueDataType.xlRangeValueDefault);

               sheetData.Add(valueArray);
            }

            return sheetData;
        }

        public void Dispose()
        {
            if (_xlApp != null)
            {
                _xlApp.Quit();

                System.Runtime.InteropServices.Marshal.ReleaseComObject(_xlBook);
                System.Runtime.InteropServices.Marshal.ReleaseComObject(_xlApp);

                GC.SuppressFinalize(_xlBook);
                GC.SuppressFinalize(_xlApp);
                GC.Collect();

                _xlBook = null;
                _xlApp = null;
            }
        }
   }
}

using (MsExcelInterop.ExcelManagement excel = new MsExcelInterop.ExcelManagement(openFileDialog1.FileName))
{
   object[,] valueArray = excel.GetSheetData().First();
}