you have to:
first: put yor form as ENCTYPE="multipart/form-data", or else it might not upload anything.
second: When uploading a file, you have the file name (say you named the FILE field in the form as $the_file), and some other info about it calling the variable with suffixes:
$the_file_name = The name of the TMP file. (use basename($the_file) to get the REAL name)
When you have all of the info, use copy like this:
copy($the_file,$the_new_file);
So, if the $the_file name is "me.txt" and $the_new_file is "you.txt", the file will be saved as two.txt
Hope it helps
fLIPIS