Want to center my featured image on homepage

I am trying to center the featured image on my homepage. I’ve browsed through some other threads of those trying to get the same thing and I’ve tried a couple of different CSS codes, but I can’t get it to work. I have installed the Simple Custom CSS plugin to try and make it easier, too. Here is a link to my temp site: http://48d.1d3.myftpupload.com/. Thanks in advance for any help!