There is a series of free videos on Youtube by Photographer Chris Bray covering many facets of Photography.  Because the videos are on Youtube there is no cost to you and me.  He goes into detail on subjects ranging from "manual mode" to ISO, to aperture.  I think you'll enjoy his indepth explanations and laid back teaching style.  If you respond better to the printed word, below are some of the manuals found at the "Digital Photography School" site.  You can find these manuals and more here:
https://resources.digital-photography-school.com/ref/937/


Whether you watch the free videos or get the manuals your photography will improve.  Personally, I like getting "freebies" and tend to buy things as a last resort unless it's something I really want badly.  See the post directly below this one to get access to the free videos.   Enjoy!