select some triggers or items, choose 'copy selected to'.
in the next window, choose "host groups" as target type :

Error in query [SELECT DISTINCT g.groupid as target_id, g.name as target_name FROM groups g, hosts_groups hg WHERE hg.groupid=g.groupid ORDER BY g.name order by target_name] [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'order by target_name' at line 1]
mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource[/srv/www/htdocs/zabbix/include/db.inc.php:519]