To sum it up, they've provided $10 and $20 donation amounts that someone can purchase in their online store.  All of the proceeds go directly to Lyn, Andy's wife, who will manage the fund for her children.  In addition, it looks like they will thank the contributors by putting their names in future book products, as actual characters or some such.  I'm not sure how that works. 

If anyone has any additional information, please feel free to share it.  And I'd like to send a shout out to our friend Jon Garceau for bringing this to my attention!