My 7 year old is making how to books today. The back page has "coming soon" and listing his other books, currently out and up and coming. I haven't explained copyrights yet, which may effect things.
The instructions range from incredibly detailed to vague. His first book has the 1st step as opening the book. Step 2: turn the page and read all other steps. The next 3-5 steps deal with finding and gathering supplies, with a helpful note that it will be hard and some items might be mistaken as garbage. Also getting yourself a secret lair to keep the creations. Several items needed in the two books I have been allowed to read: a bobby pin, popsicle sticks, glue, a broken christmas light, and the top of a Yummy Tummy drink (have your mom/dad buy you one. Then drink it, but don't throw away the lid.)
We are showing his work to trusted family and friends first before pursuing a publisher.