Pixel Bunyip

I found a Wordpress Theme on this site: http://topwpthemes.com/

How do I use this on my blog? Do I need to buy a domain and domain mapping? Does it work then? OR do I also have to get other stuff such as custom css?

Or can it work with a free blog?

It won’t work on wordpress.com blogs- they do not allow it. You will need to get standalone hosting, and use software from wordpress.org.