You are not allowed to advertise in the forums but there is a topic for asking for congratulations in the event forum. However, this may not be seen in time.

The best way to get congratulations is to go around randomly congratulating people who have been active in the past hour or sooner. A lot of players will return congratulations if they see them. If you congratulate enough players you will get the 3 you need fairly quickly returned. Start with your friends list or a player from the forums and you can then see the last 5 players who congratulated them...