Where can i learn

Where can i learn where to script a shader i can't seem to find any documentation on it can i get some help?

 

Surface Shaders (your best choice to start): http://unity3d.com/support/documentation/Components/SL-SurfaceShaders.html

Shaders in Cg: http://unifycommunity.com/wiki/index.php?title=Shaders

Tutorial about the language Cg (also useful for surface shaders): http://http.developer.nvidia.com/CgTutorial/cg_tutorial_chapter01.html

Shaders in GLSL: http://en.wikibooks.org/wiki/GLSL_Programming/Unity

Hope that helps.