Like me, most of us learn about traditional genealogy research first. DNA seems overwhelming. The truth is, doing DNA alone does not solve any genealogical questions, you still need traditional documentary research.
For example, there is nothing in an ancestor’s DNA that states when they got married or when or where they bought land. DNA can help solve questions of kinship (who a test taker is related to). With documents also, of course.
For example, if you have DNA test results of two women, and you know they have a mother/daughter relationship, and that is ALL you have, you cannot know which is the mother or daughter by DNA alone. You still need some documents to provide evidence for the proof. Birth dates, for example, for each test taker. DNA is very powerful evidence, but it must be used in conjunction with traditional documentary evidence for the old tried and true genealogy we all stated learning about first.
There are many good books out there, and I will recommend two in this post.
First, The Family Tree Guide to DNA Testing and Genetic Genealogy by Blaine T. Bettinger. Get the Second Edition if you can as it will be more recent.
This book will provide an excellent introduction to DNA and explain the different types of DNA tests available and the difference between Y-DNA, mtDNA, and atDNA. Available on Amazon and other booksellers.
After you’ve read that book, move on to a more advanced book by the same author, who worked with a co-author. Genetic Genealogy in Practice by Blaine T. Bettinger and Debbie Parker Wayne.
This book is slightly more advanced, but offers much more information. Genetic Genealogy in Practice also offers exercise questions at the end of most chapters, with answers to the questions at the end of the book. It’s like a little self-study course you can work through alone or with a study group. This book is also available on Amazon as a kindle or paperback. The book is also available directly from the National Genealogical Society as a paperback.
There are other books on DNA as well, but if you start with these, DNA will be a lot less overwhelming and start to become a lot more fun.