Richard Hill is a very fine writer. I could not put down the story of his search for his biological parents, Finding Family: My Search for Roots and the Secrets in My DNA, which reads like a mystery novel.
He has put together an e-book, Guide to DNA Testing: How to Identify Ancestors, Confirm Relationships, and Measure Ethnic Ancestry through DNA Testing, available from Amazon, which is a very simple guide to personal DNA testing. Normally $.99, it is free through 12/16.
It will help you choose which test to take and why. It is only about 30 pages. It is not comprehensive but it does answer your basic questions. It is meant for those totally new to DNA testing not for the experienced. Although if you have tested, but still have many questions, they may be answered by this book.
This may also make a nice gift for relatives who are thinking of doing DNA testing.
Please note that you can download a free kindle reader app from Amazon to your tablet or smartphone for reading this or any e-book.
For a more comprehensive book about DNA testing try Genetic Genealogy: The Basics and Beyond by Emily Aulicino. Or go through the online tutorial from Kelly Wheaton at https://sites.google.com/site/wheatonsurname/beginners-guide-to-genetic-genealogy