Many years ago, when I was just starting to learn how to use herbs, I picked up a book called 20,000 Secrets of Tea by Victoria Zak. It is a beautiful little paperback that I picked up at a discount at my local Barnes and Noble book store. That may have been one of the best investments that I ever made. I now have many books in my library on herbal medicine, but I still start with 20,000 Secrets of Tea. It is an excellent thumbnail view of a range of widely available herbs and their safe use. If you are looking for a quick reference to get you started, check it out. I can still find it if I look for it. Start with second hand book sellers. New copies are available from a number of outlets. A quick Google search will lead you to several sellers.