No sidebar on categories page

Hi, working with a designer on a wordpress site; the designer set everything up.
http://66.147.242.199/~localfl3/site/category/recipes/

I need to add advertising in the sidebar on the recipes page, it’s a categories page and I am guessing the problem is that the theme doesn’t include a sidebar on the categories page. I tried adding <?php get_sidebar( 'sidebar-primary'); ?> to the category.php file, thinking that would make it add a sidebar but no luck. Maybe I inserted it in the wrong spot, I put it after the content <div> tag.
There are a lot of hooks in the category.php file and I don’t know hooks/what to do without becoming fluent in php. Any help is much appreciated. Thanks!