ETTR is very simple: Expose to the right! That's really it. You honestly don't have to get too technical about it, and if you DO try to get too technical about it, your going to spend more time fiddling than photographing.
The concept is pretty strait forward. Noise in an image signal is a ratio of the saturation of the signal. When using a digital sensor, where exposure in post is effectively "fluid", you should maximize the saturation of your signal as best as possible, and correct the exposure in post. By "exposing to the right", you increase the number of pixels that have a higher signal to noise ratio, and thereby reduce the amount of noise in those pixels. You also put a larger percentage of the image signal above the read noise floor, and usually require a post-process exposure pull in order to correct, meaning you reduce the read noise floor even further than is otherwise the case.
The mechanics are also pretty simple. First, choose the shutter speed you REQUIRE in order to freeze the motion in your shot. Then, push ISO until your histogram reaches well into the right-most vertical box in the histogram display. You do not want the histogram to ride up the right-hand edge, and to maintain the best color fidelity in the highlights, you want the histogram to peak just a little before the right-hand edge, then fall.
Regardless of how the exposure looks when you do that, that is considered "correct exposure" in the digital world. Making the image look "correct" to human eyes is a post-processing matter, and a matter of personal taste, so don't bother trying to achieve that in camera. Just expose to the right. It's not really hard, and as you practice with it, you'll get a feel for how far to the right you can push without running the risk of clipping highlights you don't want clipped.
I also want to point out a fact about noise in regards to the processed image Marsu42 shared. He lifted the background shadows quite a bit, and revealed some banding noise. Banding noise like that is primarily a problem at the lower ISO settings. You were at ISO 200. To expose properly (without flash) you would very likely have been at ISO 800 or ISO 1600...at these settings, banding noise is extremely low to non-existent on most current Canon cameras (older cameras, like the 5D II, might still exhibit some banding at higher ISO settings.) You will still have read noise, but you'll be able to lift it more without that unsightly banding.
I use a Canon 7D myself currently, and I employ ETTR in most of my work. The 7D has terrible banding in the shadows at ISO 100, 200, and 400, but that banding is almost non-existent at ISO 800 and not present at higher ISO settings. I usually shoot at ISO 800 and above, and I often lift the shadows by several stops in photos where I try to preserve the highlights, which results in my key subject ending up mostly in the darker midtones and upper shadow tones. I never have problems with banding.