The most comprehensive source of information is the OpenGL Organization . There are a number of available HTML documents pointed to on these pages as well as pointers to vendors and FAQ.
There are a number of ways of obtaining OpenGL.
If you are using a PC, OpenGL is included with all versions of Windows. You will have to get GLUT from the web. For windows you can download just the dll, lib and .h files. You should find OpenGL32.dll and glu32.dll with your system files. You should find the corresponding lib and .h files supplied with your compiler. The corresponding GLUT files should be placed with them.
A free OpenGL is called MESA . My students have installed it successfully on a number of platforms from PCs to SUNs and have had no trouble. The API is the same as OpenGL so that code developed for my classes with MESA has transferred with no changes to many systems. Note that Mesa is a pure software implementation. One nice thing about it is that you can look at the source code to see how the various OpenGL functions are implemented. MESA is supplied with most linux distributions and most recent graphics cards have linux drivers that allow them to be used with MESA.
For other workstations, see the vendor list on the OpenGL home page.
The sample programs from the OpenGL Programmer's Guide can be ftpped from the OpenGL home page or from the GLUT distribution.
For PC linux users there are a couple of options. If you are running linux, MESA and and GLUT are included with most distributions. You can also use Cygwin under Windows. Cygwin is linux which runs under Windows. The advantage of this option is that you can use gcc or g++ but link with the Windows dll's. Recent linux drivers supplied by Nvidia, ATI, and 3DLabs have excellent performance.
For Macintosh users, OpenGL and GLUT are supplied with OSX.