access local file system of a client from asp.net web page

Its Very Urgent.
 my requirement is i want to upload my files to AmazonS3 Webserver. my code is working fine from Visual Studio. But when i host on Webserver it gives me error "Specified file does not Exists". this can be done using File Uploader Control in Asp.net. but i dont hav to use that, as my requirement is without any interface i have to upload the file. 
there is no permission isues or anything on webserver. i tried to upload file using FileUplolader Control it works fine.
i want to upload files on Webser Without any Interface. so How will webserver will understand that it has to upload a file from a specific Local Machine.
or someone tell me if there is way so we can assign path to FileUploader control so i will create object of it and assign path and will upload file usinf SaveAs() Metod of FileUploader Contrl. i cant find a way to do it.
Please help me. Thanks In Advance. Please Reply me As soon as Poss ...