Hi John,
For simple cropping and adding the bricks around the windows, you can use Paint (it comes with all versions of Windows). For something a bit more capable, free and still reasonably simple to use take a look at www.getpaint.net/
I use GIMP (free from http://www.gimp.org/)which takes a bit of getting used to, but has some very high-end features and pretty good help online. When I needed to square up a few photos it didn't take long to find an article that walked me through it in simple steps.
Cheers,
James.
(edited to fix weird URL formatting)