Originally, my big idea was to have B tell me a story about each one and I would write it for him on the back. However, it didn't really work out that way. B didn't want any part of telling or seeing a story written.
So instead I just asked questions along the way to get him talking about his pictures. I asked questions like, "What are those people doing in that tree? Are they afraid? How did they get up there?" or "Why are the cats on the roof? Are they friends with the dogs?" and "What are those people doing in the boat? Do you think they like fish or turtles better?".
This was a fun activity and there are enough stickers in the package to do it many more times.