When you think about the book Hatchet by Gary Paulsen, the story focuses on a young man whose plane crashes in the wilderness, and he must survive on his own. When trying to turn this story into a children's picture book, you must think of only the most important events in the story and picture them in your mind. If you have a young brother or sister, tell them a shortened version of the story which leaves out many of the details but includes the important information to understand. Pick out about 10 important things which must be included such as the plane crashing in the wilderness, Brian swimming out to the plane to retrieve supplies, learning how to cook for himself etc. Each detail you determine is important for understanding should become a picture with a few words below explaining the picture such as, "Brian's plane crashes by a river leaving him all alone." Use the pictures to help SHOW the children what is happening and keep the words simple but effective. Good luck.
Hatchet is a book with more mature topics, such as his mother's affair and a man dying. An idea would be to start the book with Brian being stranded in the woods. You could mention the plane crash, but leave out the pilot dying of a heart attack. Your focus could then be on searching for food, encountering wild animals, building a shelter, and so on. You could end it with Brian being rescued.