Silver Creeks reply is about the best you'll get without writing volumes. And to add to what he said, there are many books that cover the subject, depending on what you're fishing for & where.
From a tying perspective, it's easier to just start with trying to identify what might be available in the waters you're fishing, or intend to be fishing, and tie accordingly. For example, there is likely something already written, that will tell you the possible insects & other prey in your area. State natural resources websites, as well as sites from local colleges & such may have some such information.
The next step would be to spend some time on the water observing & possibly collecting some of what you find, and then identifying what you find, and tying to imitate it. A simple search once you've identified a prey species will usually give a multitude of already established fly patterns to choose from.
This can be done for any type of water, from rivers & streams to lakes & ponds, to the ocean & estuaries.
As far as "fly" types, used to be simple, it was dry flies, wet flies, nymphs, streamers, terrestrials and bass bugs or poppers, and attractors and flies for many species would fall into one or sometimes two of these categories. Now, there are so many materials to use, that there is quite a bit of overlap. Plus, within each category there are numerous sub categories which often identify a specific life cycle stage of the specimen in question particularly with regard to insects.
Like Silver said, there have been books written on it! His suggestion would be an excellent place to start!