Custom new message info in theme

Helo. Its me again.
This time i want to add to my theme new pm message beside link to messages into my theme.
I like to do it like is in user_info_panel but doesnt work.
When i add this to my theme.php i have error:

Notice: Undefined variable: userdata

Ok. But what i must do?

I have:

$msg_count = dbcount("(message_id)", DB_MESSAGES, "message_to='".$userdata['user_id']."' AND message_read='0'AND message_folder='0'");

and

if ($msg_count) { echo "<a href='".BASEDIR."messages.php' class='side'>".sprintf($locale['global_125'], $msg_count).($msg_count == 1)."</a>\n"; }