Also, you can say:
1. In this picture, a girl is helping her grandmother get out of a car which reminds us of how important it is to be there for our elders.
2. In this picture, a boy has been killed in a car accident because he wasn't wearing his seatbelt; therefore, I believe its message is that you could be dead at any moment so you shouldn't take safety lightly.
Sorry, I just realized that I didn't know if you wanted examples of sentences describing what is happening in a picture or ones stating the picture's meaning / message. Anyhow, these two do both. :)