[TECK]

FIND:

// if user is know, then welcome

BELOW, ADD:

$countnewthreads = $DB_site->query_first("
  SELECT COUNT(*) AS total
  FROM thread
  WHERE dateline>$bbuserinfo[lastvisit]
");
$countnewposts = $DB_site->query_first("
  SELECT COUNT(*) AS total
  FROM post
  WHERE dateline>$bbuserinfo[lastvisit]
");
$getnewthread = number_format( $countnewthreads['total'] );
$getnewpost = number_format( $countnewposts['total'] );

Then use the 2 $getnewthread and $getnewpost variables in your template.