Editing under/over expose picture

For those who are new to SLR will experience under/over expose a lot and many will just delete the under/over expose picture. I, myself wont simply delete any picture until I have seen it on a larger scale (19" monitor). From there on only will I decide to delete it or to keep it for editing purpose. I'm not a big fan of editing but on some picture (shown below) it is necessary to do so. lets see what we can do with under/over expose picture with only a few simple steps.

 This is the original picture

The rest are done with only 2-3 steps from photoscape and even picture manager.