ASPX C＃如何下载用户需要的文件？

I am trying to develop a web page which will allow users to download to the Directory of there Choice. In my search to find away to do this, I had found that you can't use "FolderBrowserDialog". I am also finding that the examples online will only search the websrver directeory path and not the local machine. Is there anyway to get the Directory Path? I have the code to FTP the File Down, I just have to replace the code for "FolderBrowserDialog".I am trying to develop a web page which will al