Sounds like you may want to look up the html tag:
<input type="file"
This tag pops up a dialog box that allows the user to search through his hard drive folder structure for a particular file. The dialog box also contains a button to allow him to send the contents of the file to the server. There is no need to create your own folder tree. You'll have to look on-line on how it works and what code to put on the server to support it.>