How to write code for file upload control

Dear karthik

please refer below link for Asycfile upload control

http://www.c-sharpcorner.com/Blogs/7361/file-upload-control-using-ajax-and-javascript-in-Asp-Net.aspx

in cs
if (fileup.HasFile)
                    {
                        //if pic path is specified in file upload box, then save picture
                        try
                        {
                           
                            string file="pic";
                            string filename = file + '_' + fileup.PostedFile.FileName;// file name will be pic_abc.jpg
                            filename = filename.Replace(" ", "");
                           
                            fileup.PostedFile.SaveAs(Server.MapPath("~/image/") + filename);
                           

                        }

in design

                               
                                                                    ControlToValidate="fileup" ErrorMessage="*" ValidationGroup="aaa">
                                                                ValidationExpression="^.*\.((j|J)(p|P)(e|E)?(g|G)|(g|G)(i|I)(f|F)|(p|P)(n|N)(g|G))$"
                               ControlToValidate="fileup" ValidationGroup="aaa">