Can someone point me in the right direction to create an upload page used for commercial use? I would like to create a page where a client, authenticated by username and password, can upload files. It would be like this:

1) User logs in
2) User designates file(s) to upload
3) Depending on user, uploaded file(s) go to appropriate folder on server.

I don't need anyone to do it for me, just point me to some useful information or to give some useful information. Thanks, Jeremy