what are the basic needs for a beginner? how do we start using opengl?
Good knowledges about a programmation language are a necessity. This will often be C or C++. But you can use other languages too, however I won’t be able to talk you about those others. OpenGL is not written in C++, so C might be best for you in order to start.
Good knowledges in mathematics are important too. If you know how to play with vectors, how to calculate rotations, it’s well. If you know vectorial spaces, matrices and quaternions, it’s best.
Then, good documenation about this libraries are important too. Generally the OpenGL reference manual is the prefered choice of plenty of us.
Hope this helps.
You will find lots of information on this website, the opengl spec. is available for download as a pdf file, always good to have around.
And you can find tons of tutorials using google or other search engines, search for “opengl” and “tutorial(s)”.
Most common C/C++ compilers comes with all the files you need (Visual Studio, MinGW and others).
If you havent already, you might want to check out NeHe here It has good tutorials for OpenGL on the windows OS, (and maybe linux?)