What You saw there is a template for a wordpress installation.
To use that You need wordpress and the template.
But I really recommend You to load the script from this site here. This is a complete product, only made for questions and answers.
This is much better than the template together with wordpress !!
The q2a script here is 10 times faster and much easier to handle than the wordpress option. Besides wordpress installations have big problems with automatted spam submissions. I tried to build a Q&A site with wordpress and it was to complicated to get it running fast and secure. The Q2A script here is out of my personal view the best script available actually.
If You want a theme for the q2a script You can make it as described in the instructions on this site here.
To see how this script here can look see the users, and some of them have links to their sites made with Q2A