Large Featured Image

Trying to get the full size of the main image to show up, in full, on the home page. I switched the .css file, as per the previous thread. After tinkering with the dimensions, I was able to get the thumbnails to be the right size, but my main image (top line – top left corner) is jacked. (http://sports-gifts-shop.com)

I’m not the smartest when it comes to coding and whatnot, I usually outsource it. Any advice/help is appreciated.