Lighting a scene with an hdri image could not be easier. All you need is a quality hdri that suites the mood/look you're going for, after that the work is pretty much done. You can even get the hdri to act like a sun, lowering the gamma gives the hdri more contrast, makes it stronger and give you a harder shadow just like the sun. Keep in mind that if you have an hdri image of lower quality you might get a bad result. I know you are very eager to become the next top graphic artist and there for lowering the gamma abit too much just because you can, don't. You surpassing my awesomeness is something i just can't accept. Rock on friends!