$target_path="./upload/";

$tmp_name = $_FILES[ "champ_fichier" ][ "tmp_name" ];
$dest_file_name = $target_path . basename( $_FILES[ 'champ_fichier' ][ 'name' ]); 
if (move_uploaded_file( $tmp_name, $dest_file_name ) ) {
	// ok
} else {
	// error
}