Get halfway through a model and find it's an unworkable mess? Can't add edge loops where you need them? Can't subdivide a mesh properly? If any of this sounds familiar check this course out.
As for dispersion:
the new version of l_glass shader has dispersion attribute, (I mean l_glass v2 beta version, not the 1.2 version) but boy it takes long to render!!!
Don't have time right now to play with it but you might try
here are screen grabs of some settings I used. all in all you can´t don wrong with l_glas cause it´s a fancy tool. the to get the most out of your renderings the light setup is crusial. the shader lives from reflections so I made a box with lots of spotlights to get the reflections I needed. tweaking the light setup it took me about 1-2 days I guess.
just play around and watch out for good lighting tutorials, cause thats many times more important than the shadersettings.