A great beginner's book. Does contain mature content. A great catch-all for beginners as it will discuss fundamentalsof practice that can be applied across the board. Depending on your interests, I can recommend other books as well.
If you will be more specific about exactly what it is you wish to read books about we would be more apt to provide you with some truly useful titles. Given your current request I could recommend anything from "Tom Sawyer" to the Koran, to a textbook on mathematics.
I'm looking to understand pagan and wiccan as a whole as well as what are specific topics I should be focusing on first and how I can read and learn where I want my place to be.
First of all, the term Pagan refers to a wide variety of different religions both ancient and modern. Some of the modern, Pagan religions include Asatru, Druidry, Heathenism, Celtic Reconstructionism, Hellenismos, Kemetic Reconstructionism, and Wicca.
Wicca is one, specific religion under the Pagan umbrella. As such it has some very specific beliefs and practices. Wicca was put together by Gerald Gardner in the 1940's; although it is based on earlier folk magic. You might want to look at the post What Wicca Is and Isn't at https://www.spellsofmagic.com/read_post.html?post=637268 I've been a practicing Wiccan for nearly 40 years now. If you have specific questions about Wicca, feel free to ask me. Also, do check out some of the pinned posts in the Wicca Forum.
As for books for someone starting out in Wicca, I would recommend these:
"Wicca: A Year and a Day" by Timothy Roderick
"Wicca" by Thea Sabin
"The Witches' Bible" by Janet and Stewart Farrar
I personally do not recommend books by Edain McCoy, Silver Ravenwolf, D.J. Conway, Sirona Knight, and a few others because of the misinformation they contain.
