You add what's in red :
$result = sql_query("SELECT sid, title,time,informant FROM ".$prefix."_stories ORDER BY sid DESC limit 10", $dbi);
...
list($sid, $title,$date_time,$informant) = sql_fetch_row($result, $dbi);
...
and then after the line
echo "<title>".htmlspecialchars($title)."</title>\n";
you can add the two lines :
echo "<date>".htmlspecialchars($date_time)."</date>\n";
echo "<informant>".htmlspecialchars($informant)."</informant>\n";
for instance