$handle = fopen($file,"w");
$text = "<tr>";
$text .= "<td>{$POST['map_name']}</td>";
$text .= "<td>{$POST['game_host']}</td>";
$text .= IsTrue() . "\n";
@fwrite($handle,$text);
fclose($handle);
It should look something simliar to this. This will work if you have the correct permissions to write to the file.
Take out the @ in front of fwrite and see what error you receive.
Cheers