C++ doesn't have any built in graphics. There are moves afoot, heavily driven by Herb Sutter, to add graphics to a future C++ standard (C++ 17, perhaps).
If you want to show somethig on screen, ultimately you ask the operating system to ask the graphics driver to do it for you. This is how all (modern) programming languages do it. In C++, you can interact with the graphics card yourself (massively low-level, don't try it) or ask the operating system to do it (so start reading up on your operating system APIs), or you can get another library (for example, SFML, SDL, Cairo); you use that library, it talks to the operating system for you.
Do you actually want to do serious graphics, or do you want to make GUIs? If the latter, a "widget toolkit" might be what you're looking for.
graphics.h was a header originally provided with a particular C++ compiler, about twenty five years ago, for doing simple graphics on DOS. Being a header, it of course came with a library behind it to link against. A library for DOS, which was a kind of operating system from before you were born, I'm guessing.
So you've asked me for a simple graphics library that uses a header named "graphics.h"
That's a remarkably specific request to make. I'm going to guess that you use windows. As chance would have it, someone has made a windows graphics library for C++ that uses a header named "graphics.h"
As someone totally new, you'd do better to start by learning and getting experience in programming before you moved on to graphics with C++. If you want to skip ahead, Cairo would (probably) be a better choice for a beginner than openGL, but it does depend on what you actually want to do. What do you want to show on the screen?