Import or Export DataGrid to Excel or HTML files from your .NET applications

Visual Basic .NET code:
Dim ef As New ExcelFile
Dim dataTable As DataTable = DirectCast(dataGrid1.DataSource, DataTable)

' Depending on the format of the input file, you need to change this:
dataTable.Columns.Add("FirstName", GetType(String))
dataTable.Columns.Add("LastName", GetType(String))

' Load Excel file.
ef.LoadXls("FileName.xls")

' Select the first worksheet from the file.
Dim ws As ExcelWorksheet = ef.Worksheets(0)

' Extract the data from the worksheet to the DataTable (DataGrid).
' Data is extracted starting at first row and first column for 10 rows or until the first empty row appears.
ws.ExtractToDataTable(dataTable, 10, ExtractDataOptions.StopAtFirstEmptyRow, ws.Rows(0), ws.Columns(0))

' Change the value of the first cell in the DataTable (DataGrid).
dataTable.Rows(0)(0) = "Hello world!"

' Insert the data from DataTable to the worksheet starting at cell "A1".
ws.InsertDataTable(dataTable, "A1", True)

' Save the file to XLS format.
ef.SaveXls("DataGrid.xls")