In most traditions, there is no original source material. Many traditions were secretive, and kept close control on texts, holding control to the clergy. In many other cultures, tradition was oral, and never written down. In some, things have changed significantly.
What results is a very broad difference between mystical history of a tradition and actual history. Type of mysticism may also change over time, and is historically observable as such.
But remember: Spells are not magic. Many traditions never use spells. Some people do chose to use spells, and sometimes spells are part of traditions. Some traditions do things similar to spells but with different names.
Your best bet is learning what magic is, how it works, and start a regular practice. Do a bit of research, learn about different traditions, and see which direction you want to take. OF course, studying a different tradition later is also perfectly fine.