If you're interested in writing a renderer yourself (which is obviously way cooler than using some tools), I'd recommend first picking up either "Fundamentals of Computer Graphics" by Shirley and Marschner or "Computer Graphics: Principles & Practices" by Foley and Van Dam. Once you understand the basics of computer graphics and especially of shading and ray tracing, I'd recommend picking up "Physically Based Rendering: From theory to implementation" by Pharr and Humphreys which is an excellent book that explains the State of the Art of photorealistic rendering. Once you understand how physically based rendering, path tracing, BSDFs and all that good stuff works you're ready to write your own rendering (or to implement a new SIGGRAPH paper in the framework provided by the book). It's a lot of fun writing your own renderer and you'll produce some beautiful pictures.