Format my picture book

I require expert advice on how to make my text and illustrations print-ready. I have written a picture book and arranged illustrations, so now I need it to be formatted for production as a book. As a teacher for many years, I would like a professional-looking book suitable to take into schools to share.
My story is a humorous romp across the Countryside as Gran and Mia chase Gran's pants which are blown away during a hurricane. Gran is embarrassed until she realizes pants can be useful-who knew?