The edit is fine, just be careful with the lower portion of the sky that you miss with the gradient because of his head.
This is something best done in LR as you have done (or your raw processor of choice) as you're working with the raw file rather than a PSD or TIFF, so you've obviously got more data to play with.
@Amin; Open up your TIFF (I'd use a PSD, much better file sizes) go to the adjustment layers tab and select exposure or curves. That will open up its own little options palette, make your adjustments, so pull the exposure down, or pull the middle of the curve down to darken the image.
Then click on the white rectangle on the adjustment layer in the layers palette (this would be easier to show with screen grabs, but I'm being lazy, sorry) this is the mask for that layer. Take a black brush and paint over anywhere you don't want darkened, it will cancel / mask out the effects of the adjustment layer, revealing the original underneath.
Use a soft brush and different shades of grey to get nice transitions and to have fine control over the adjustments. If you want to go back, just paint white back in, much better than erasing stuff that you can't get back.
That's the very basics of it, you could also generate two different PSDs from your raw file and use the same techniques to blend them, but if you can do it well enough in your raw editor it's probably not worth the time.