Well, there's really no need for an in depth tutorial for the GUI or the emitter based lights. The GUI only is capable of changing a couple of settings relating to how Lux actually renders out the image, the tone mapping (which can be done at render time anyway), output name and directory to export to. Recommended settings are highly dependent on how you want your render to look and for the overall scene itself. Generally speaking, outdoor scenes work well with bi-directional and metropolis settings enabled, indoors vary depending on how much light is needed.

As for emitters, as it's already mentioned before, they are currently dependent on an ambient color and it's strength from 0.1 to 1. If it's allowed, you can increase it beyond the maximum. Also, if you're going to be using emitter lights, I recommend using them in conjunction with one environmental light with a hdr map attached to it. For the most part, mixing those two types will allow for your scene to get enough light to make objects visible and then receive shadows and additional lighting from the emitters. You can also adjust them at render time in the lighting tab.