This is the text I used in my graphics class. It's *very* good and covers all the fundamentals. Even if you don't study the entire book, which is quite an undertaking, it's helpful to have the theory and math at hand when you're trying to learn.
Also, if you're really interested in graphics, it helps to study, at a minimum, optics. There are some free ebooks by Benjamin Crowell on physics that might be helpful,
Light and Matter: open-source physics textbooks.
To actually do graphics, there are many many options. Even though you might be using C++ for the bulk of a program, many times you'll be using other languages as well. Virtually all modern game engines use a scripting language to handle events and AI.
But the real question is what sort of graphics are you interested in?
2D, 3D? User interfaces? CAD? Drawing programs? Photo manipulation? Image processing? Video processing? Codec development?
What platform do you want to work on? DirectX? OpenGL? X11? In a web browser?
How are things supposed to work? In realtime? Pre-rendered? Ray-traced? In robotics? Embedded?
Let me know (and try putting some terms through a search engine) and maybe we can narrow it down. I'm (obviously) not an expert in all these fields, but I can probably be of some assistance.