The native Books app is "difficult" to use unless you are downloading titles from the Apple Store. Especially since Apple decided to split up the functions of iTunes and make Books a seperate application.
You will find that most providers of eBooks will also provide a suitable player for their publications. In the end it is by far the easiest way to go but requires a subscription. Alternatively check your local library, here in Australia a public library membership is free and they also stock audio books and advise apps (cheap) that are suitable for use on portable devices.
Thanks Patrick, I emailed a couple books to my 90 yr. old mom & got them via iCloud & into the books app. I will explore the video further to find a smoother way later. She is happy now, thats all that counts!