Hi
I would recommend looking at shaders online such as the ones provided by the "Otter Examples" and play around with them to get a little used to GLSL. As to a tutorial i would recommend something im pretty sure you already looked up
www.opengl.org/sdk/docs/tutorials/TyphoonLabs/Chapter_1.pdf. Note that i've never followed those tutorials myself, but giving it a quick look seems something ok to recommend. Also, SFML doesnt have support to a specific GLSL version, as you can see on this answer on the SFML forum
...SFML doesn't support anything, it rather depends on the target graphics card.
Some GPUs may not support shaders at all, some others may support it but with a limited set of GLSL instructions...
*If it caused any confusion talking about SFML rather than Otter*
-SFML handles the shader
-Otter provides the vertex and fragment files and uses them to create a SFML shader that you can later use as the Otter "Shader" class
That's about it. Sorry i couldnt give much 'valuable advice'.