DataTable dt = new DataTable();
        dt.Columns.Add("empid");
        dt.Columns.Add("empname");            
        foreach (GridViewRow row in GridView1.Rows)
        {
            CheckBox chk = (CheckBox)row.FindControl("CheckBox1");
            if (chk.Checked == true)
            {
              int i = row.RowIndex;
              Label lbl = (Label)GridView1.Rows[i].FindControl("Label1");
              Label lbl1 = (Label)GridView1.Rows[i].FindControl("Label2");
              DataRow dr = dt.NewRow();
              dr["empid"] = Convert.ToString(lbl.Text);
              dr["empname"] = Convert.ToString(lbl1.Text);
              dt.Rows.Add(dr);
            }
        }
        GridView GridView1= new GridView()
        GridView1.DataSource = dt;
        GridView1.DataBind();
        Response.Clear();
        Response.Buffer = true;
        Response.ContentType = "application/ms-excel";
        Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.xls", "selectedrows"));
        Response.Charset = "";
        System.IO.StringWriter stringwriter = new StringWriter();
        HtmlTextWriter htmlwriter = new HtmlTextWriter(stringwriter);
        gd.RenderControl(htmlwriter);
        Response.Write(stringwriter.ToString());
        Response.End();