I want to Learn GLSL shaders

could anyone please tell me where i could find a good & free book to learn GLSL shaders.I did try to learn it through tutorials but its to advancd for me i can understand only a little and rest goes over my head.please help me!also i would like to ask that does these shaders require very much computing power? will i be able run them properly in my dual core pc with shader model 1.0 ?

Hello
here is the home of OpenGL:
http://www.opengl.org/
just enter GLSL in the search field and you’ll get plenty of information
Good luck, be brave!
Bye

Okay, I’ve started learning GLSL now but still I did not find very good resources to learn it. I was reading an article about GLSL on NeHe productions site and in have done this copy-pasta job from there:

There are four main types: float, int, bool and sampler. For the first three types, vector types are available:
vec2, vec3, vec4 2D, 3D and 4D floating point vector
ivec2, ivec3, ivec4 2D, 3D and 4D integer vector
bvec2, bvec3, bvec4 2D, 3D and 4D boolean vectors
For floats here are also matrix types:
mat2, mat3, mat4 2x2, 3x3, 4x4 floating point matrix
Samplers are types representing textures. They are used for texture sampling. Sampler types have to be uniform. They are not allowed to be declared as a non-uniform type. Here are the different sampler types:
sampler1D, sampler2D, sampler3D 1D, 2D and 3D texture
samplerCube Cube Map texture
sampler1Dshadow, sampler2Dshadow 1D and 2D depth-component texture

Now to be honest I did not understand anything except a few lines of explianation.

1. I’ve learnt about float, int, Boolean data type in my little study of C++ as well as in Action script but what is Sampler?
2. What is vector and what are these 2d, 3d and 4d floating vector points are they something like multidimensional arrays. Integer and Boolean vectors???
3. 1D, 2d and 3d texture ? aren’t textures only 2d?
4. Is cube map texture something like the way in which cube gets unwrapped in UV editor?
5. What are matrixes? Are they matrix of math if yes then still me what they are because matrix is in 11th class syllabus and I’m still in 10th.
6. 1d and and 2d shadow? I’ve never seen a width less shadow.
I still have 100s of question to ask but I’m tired now. Good Night.