Editing manuscripts and uploading onto Kindle

I've taken on a new task, and that is to edit a children's story, create a cover for it, and upload it onto Kindle or Smashwords. I'm doing it for two reasons. One is as a favor to a friend, the other is to teach myself how to transfer a book onto Kindle or Smashwords. I haven't decided which format I want to use yet. I figure when I get to that point, I'll make the decision then. In the meantime, I have my hands full in editing, and in some places, even rewriting segments of the story. One of the things I've come across in my editing endeavor, is the focus of the story, or the lack of it. I never gave it much thought until I realized this story was rambling all over the place and if a child were to be reading it, he or she would become confused. This is definitley a case where less is more. Less chit chat, and more focus on the movement of the story. Since I write adult fiction, I'm keenly aware of my lack of expertise in this field. I'm not worrying so much at this point on using words that may be beyond a young childs comprehension, but focusing on the quality of the story. I hope to keep my followers posted on my progress on this project. If anyone has any questions, or advice, I welcome both.