I normally don't do AAR's however, the one you linked to was very sharp looking. I too, would love to know what program was used for that AAR.
I have used paint.net for all of my image editing, for several years. Paint.net is always available for free as it is an open source program.
Here is a direct page that the download link is advertised. If you decide to download it, make sure you use the proper link, which is the one on the right side of the page that says "paint.net 4.0.3", as the other links appear to be for pop-up adds.
http://www.dotpdn.com/downloads/pdn.html
Another free program I use all the time is called "Color Cop" and it is a real good program to use when you are trying to get the exact color code off of any color you what to use.
http://colorcop.net/download
As for picture taking/screen shots, all you do is select "Shift", "CTRL", or "alt" and next select "prt sc" to take a screen shot. Next, open paint.net or any other program and select "paste" and your screen shot will appear in the paint program you are using. Next, just name the image so it is your "original". Next, edit the pic and make sure to save it as a different name, so you don't ruin your original.