Tips for learning how to make my own shaders

Hi Everyone,

I've been studying Max and jitter for almost half a year now and just about everything I do is with the OpenGl objects.

I use 3d models that are run through instances of jit.gl.slab and have finally decided its time to get my hands dirty with learning how to write my own shaders.
I tried the tut from Andrew (how to write your 1st shader) and couldn't finish it, to me it wasn't clear enough for a complete beginner. example below.

" The program tag allows you to specify a vertex and a fragment program for your shader. Using the “source” argument, you can specify another file for a specific program. In this case we are using “sh.passthrudim.vp.glsl” vertex program, which is one of several handy little utilities in the “jitter-shaders/shared” folder. This particular one just does some basic setup work for you and passes some useful variables to the fragment program."

So I have no idea what that means and why I would use it ! (I found the file “sh.passthrudim.vp.glsl”, checked it out and came to the conclusion it was beyond me !)

So after browsing around the forums and the web I have the following questions.

1 - Where can i learn how to make a shader which explains "everything" i'm doing ?? Should I try and dive into this massive monolith called the orange book or the openGL super bible ?

2 - Any tips on how to learn how to make shaders specifically for jit.gl.slab ??
I've noticed theres a lot of differences between making a shader for a web browser and one for jit.gl.slab.

3 - https://www.shadertoy.com is an incredible site to me. Is it possible to translate these shaders into the world of jitter with jit.gl.slab ??

4 - What version of OpenGL do's Jitter use, and how can i find it out ??

I have no problem studying to learn all these things I just need some pointers so I don't learn "the wrong things".

So any links, book references and such would be greatly appreciated.

Massive thanks in advance

Andro