create auxiliary buffers

I am trying to create auxiliary buffers but I got errors like these ones:

error C3861: ‘glGenBuffers’: identifier not found
error C2065: ‘GL_ARRAY_BUFFER’ : undeclared identifier
error C3861: ‘glBindBuffer’: identifier not found

I added the headers: glew.h , glext.h , and wglext.h
Also, GL/glut.h is included

The functions are declaired in the included files, but not defined anywhere. Can anyone tell me how to use these functions? and how to set an index buffer ?
Your help would be highly appreciated