I have to questions I hope someone can help me with..

How can I display the Who is Online on every page?
is it possible to display the Who is Online part of the web site, on each page? I tried to use the same code, but then it does not come up.. what do I need to do?

Need help with five latest posts php code
I need the code to get the Five latest posts up on my web site, and the code to get the Five latest started topics up on my web site.

What PHP code can I use?

Can I use something like this? :
{
$prefix = 'p';
$sql = "SELECT x.post_subject as title, p.post_id as id, f.forum_id, t.topic_title as more "
."FROM ${table_prefix}topics t, ${table_prefix}forums f, ${table_prefix}posts p, ${table_prefix}posts_text x "
."WHERE t.topic_id = p.topic_id AND f.forum_id = t.forum_id AND p.post_id = x.post_id "
."ORDER BY p.post_id DESC "
."LIMIT $count";
}


Please help!