There are two paths on two different computers. First is on the client machine. On the server you can't known his local system path, web browser doesn't send this information to the server, for security purposes.
The second is path to file on server after web browser uploaded it. You should use function move_uploaded_file() with directory, where you want this file to be stored. Before that the file is temporary saved in directory specified in php config file under directive "upload_tmp_dir".
More info in PHP manual