You need to add a Category Blog menu item and there add an image to the Page Title options. But interestingly, on your site Category Blog menu item is missing. This refers to Joomla error. I hope that installing latest Joomla will solve this issue. If not solved, then check this discussion
Please install Indigo Quickstart on your localhost and check Secondary Menu and check Blog Menu Item. There is the image added in the Page Title settings and is shown at the top of the Blog page. So, you have to follow exactly like in the quickstart.