This news comes couresty of the AKB48 Official LINE account. Voting appears to be over, but basically this was a contest to vote for the top user-submitted Kokoro No Placard messages.
The first place submission appears below. I felt it was worth mentioning, as it’s a very touching message.

It reads:
To my father in heaven (天国のパパへ)
I’ve finally gotten married! (やっと結婚できました!)
He’s a lot like you.(少しパパに似ている人です。)
I wish you could have met him.(会って欲しかったー!)
How nice (^^. I wonder if there will be future events like these.
Author: jerry
Sometimes editor. Sometimes translator. Mostly a proofreader. I like Japan and things.