Share on Facebook code

I've created a series of personality quizzes.

I simply want a button that allows users to be able to share their results on Facebook.

So for example, if someone took the quiz, 'What 80's Hunk are you?' and the result came out 'Your 80's Hunk is Michael J. Fox', I want them to be able to click a button, which automatically creates the Facebook post 'My 80's Hunk is Michael J. Fox' with the image from the result page and a link back to the quiz itself.

Here's an example of a results page from another site, which has such a button:

http://www.blogthings.com/whatdoesyourchristmastreesayaboutyouquiz/results/?rone=1&rtwo=2&rthree=2&rfour=1#

Clicking the Facebook icon on that page creates the exact functionality I'm looking for.