[C# .net 4] Create Excel file using OpenXML

hi there, hope in your help.

i need Create Excel file in ASP.NET C# using OpenXML and this is my example link:

http://www.c-sharpcorner.com/uploadfile/jayendra/how-to-create-excel-file-in-asp-net-c-sharp/

i tried this code but i have error:

CS0246: The type or namespace name 'OpenXmlDataDataContext' could not
be found (are you missing a using directive or an assembly reference?)


Can you help me?
Any other suggestion for my problem?
Thanks