Hi Vishnu, first I want to point out that the code that Rahul provided actually creates a HTML content and exports it into a file with XLS extension. MS Excel is able to read HTML content so that is why this approach works.
Now the main thing here is the "Page.RenderControl(hw)" call which will retrieve the actual HTML representation of some web control (in this case the Page), but in order to successfully call this method you need override the "VerifyRenderingInServerForm", like the following:

public override void VerifyRenderingInServerForm(Control control) { }

And also you need to disable "EnableEventValidation" on the Page, like the following:

<%@ Page EnableEventValidation="false" ...

In case you need a real excel file then you will have to use some other approach, note that you can find some .NET libraries that can help you out with this.
For example you can try out this Excel library for .NET, it can convert the HTML content into an excel file in .NET and then you can export that excel file in ASP.NET.

Thanks sir,
You are correct but when i call it on page load the blank excel will generate please give me full code.

http://www.codeproject.com/Tips/732232/Export-to-Excel-in-ASP-NET-Csharp
http://www.c-sharpcorner.com/UploadFile/ankurmalik123/export-html-to-excel-and-more/

Actually this code is used for store the web page content in excel file using .net where 'RepeaterExport.xls' named excel will generate and  'Page.RenderControl(hw)' will render your page content in htmltextwriter.

I will try to extract the other website to excel.

Rahul sir ,
Your code is only open blank excel file

Hello Sir,
My Question is not to upload the excel file in application my question is to store the web page content in excel file using .net and this will be done when i click on any other link that are in my application ex.suppose i click on google.com then google page will open and the content of google page will save in excel this will be done automaticaly after i click on link.

try this code after adding 1 namespace

using System.IO;

  public void expgrid()
    {
       Response.Clear();
        Response.Buffer = true;
        Response.AddHeader("content-disposition", "attachment;filename=RepeaterExport.xls");
        Response.Charset = "";
        Response.ContentType = "application/vnd.ms-excel";
        StringWriter sw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(sw);
        Page.RenderControl(hw);
        Response.Output.Write(sw.ToString());
        Response.Flush();
        Response.End();
}