I am trying to compile a program which includes the
In file included from firstc.c:2:0:
fatal error: sstream: No such file or directory compilation
graphics.h is a non-standard header. Most likely it refers to the old BGI graphics library of the Turbo C DOS compiler. It will only work on that particular compiler. And of course DOS is a completely obsolete OS nowadays.
If you are interested in 3D graphics programming, then OpenGL and/or DirectX are indeed better, modern alternatives, supported by many compilers.