Something like this should work.
PHP Code:
$numbersmembers=$DB_site->query_first('SELECT COUNT(*) AS users,MAX(userid) AS max FROM user');
$numbermembers=number_format($numbersmembers['users']);
$countposts=$DB_site->query_first('SELECT COUNT(*) AS posts FROM post');
$totalposts=number_format($countposts['posts']);
$countthreads=$DB_site->query_first('SELECT COUNT(*) AS threads FROM thread');
$totalthreads=number_format($countthreads['threads']);
And use
$totalthreads $totalposts $numbermembers,
In the templates...