Is it better to center align section headings or left align?

I have this page: http://www.problemio.com/problems/problem.php?problem_id=161

On the right side I have a few sections like "page stats" "recommend" "problem categories"

what I am wondering is whether it is better to center align the section headings or left-align them?

Also, whats the best way for me to capture the screen shot so I can post it here instead of the link to the site? I don't have Word which I know you can save the screen shot to, and I am on a pc.