By “method unvailable” I assume you mean that the code doesn’t compile because the declarations are missing?
The Windows(R) gl.h contains declarations of the OpenGL(R) 1.1 functions and constants, implemented in opengl32.dll.
When using newer functions, you have to declare the apropriate function pointers and use the wglGetProcAddress function, implemented in opengl32.dll and
declared in the system header, to load the functions.
There are dozens of libraries out there that can do that for you. I personally recomend GLEW