Yeah, sorry about that. But there is nothing else you can do other than to try and try hard to understand the available resources.
Look for demos, tutorials (video tutorials on YouTube by ThinMatrix for example), articles and specifications, buy books about OpenGL (for example the "The OpenGLĀ® Programming Guide", also known as "the red book").
It will take time, effort and practice to learn it.
But the resources already available to you on the internet (first-page google results) are good.