How to add PHPBB3 Code..

Hi all..
Its difficult for me , to understand how to add any codes and what type of code is it (CSS,script,html..)
That is the code , whose i want to put to my site , please try explanation in detail , what i need to do and where i need to put that code (Sorry for my English , im not very well in that language)

Code:

<?php[size=12][/size]
[size=12][/size]
$connection = mysql_connect("localhost", "root", "pass");[size=12][/size]
$db = mysql_select_db("database", $connection);[size=12][/size]
[size=12][/size]
[size=12][/size]
$query = mysql_query("select * from phpbb_topics order by topic_time desc limit 0,5");[size=12][/size]
while($rows = mysql_fetch_array($query))[size=12][/size]
{[size=12][/size]
$qry = mysql_query("select * from phpbb_forums where forum_id='$rows[forum_id]'");[size=12][/size]
$rwz = mysql_fetch_array($qry);[size=12][/size]
$forum = $rwz[forum_name];[size=12][/size]
$catid = $rwz[cat_id];[size=12][/size]
$qry2 = mysql_query("select * from phpbb_categories where cat_id='$catid'");[size=12][/size]
$cat = $rwz2[cat_title];[size=12][/size]
echo "[size=12][/size]
<table>[size=12][/size]
<tr>[size=12][/size]
<td>[size=12][/size]
<font face="Verdana" color="#006699" size="2"><a href="forum/viewtopic.php?t=".$rows[topic_id]."">$rows[topic_title]</a></front> ($rows[topic_replies])[size=12][/size]
</td>[size=12][/size]
</tr>[size=12][/size]
</table><hr>";[size=12][/size]
}[size=12][/size]
[size=12][/size]
?>

That is a code for "Last Topics"...
Thank you beforehand.

@rago12 is this now solved ?