Should I learn WebGL or OpenGL?

There are some differences between OpenGL and WebGL. However, if you learn OpenGL, you will be able to pick up WebGL very, very quickly.

Most likely you will use either C, C++, Objective-C or Java while learning OpenGL. For you to work with WebGL you will need to learn Javascript.

For either OpenGL or WebGL, you will need to learn the OpenGL Shading Language (GLSL) as well.

So just pick one and have fun.

How do I learn the basics of Computer Graphics

If you are interested in learning the basics of Computer Graphics, you will need to start learning the basics of Linear Algebra. Concepts such as vectors, matrices and transformations form the basics of computer graphics.
For example, when you press a button on your controller to rotate a game character on a screen, you are applying a rotational transformation to the...

What tools do you need to develop a 2D mobile game

Assuming that you want to design a 2D game, you will need a 2D game engine such as Cocos2D. The engine will take care of all the OpenGL calls, so you can just focus on the design of your game. 

A really good book on Cocos2d for iOS devices is

From Model Space to Screen Space- OpenGL Space Transformations

Transformations are not only used to rotate, scale or skew a coordinate system. They are also used to completely transform a coordinate system into a totally different coordinate system. For example, transforming a 3D coordinate system into a 2D coordinate system. This is what OpenGL does. It converts the 3D coordinate system of a character into a

Demystifying OpenGL Shaders

What is a shader? a shader is a small program developed by you that lives in the GPU. A shader is written in a special graphics language called **OpenGL Shading Language** (GLSL). A shader takes the place of two important stages in the OpenGL pipeline: