This is a tutorial about php file uploading:
http://www.tizag.com/phpT/fileupload.php
And register_globals is EVIL! Whoever invented it should :gtfo2: ...
When you have an url such as file.php?var=1 you can access the var by $_GET['var'] or $_request['var'], if register globals is on, $var would be the same! And what's even worse, it's a GLOBAL! In your whole file.php $var would have the same contents (1), this is extremely useful for a hacker, not to mention if you have an $var in the main loop and an $var in a function, they will have the same contents, which is probably not a good thing...
So just leave register globals off... (Yes, x10 has it turned off.)