It really doesn't entail much of anything.
Just whenever you feel like it, pick someone from the member list to send a RAK (random act of kindness) card.
I've sent some and received many lovely cards.
Members birthdays are posted if they wish. So you can pick someone or two or three to send a birthday greeting to.
That's all there is to it. And it's so nice to make someone's day by sending them a card.