Facebook Link Picture?

This might be in the wrong section…

I was curious if there is something special you need to do in your theme or account so that when someone posts your domain http://www.yoursite.com in a post on Facebook you can choose the picture as well as the link.

Currently I try to share my site on Facebook it redirects to a post and shows an image that doesn’t even exist on my site not giving a very impressionable impression when users try to share my site.

I have no idea what I am doing wrong.

site in question is http://www.doucheon.com/