If you’re going to add any widgets to any Bootstrap-based theme, even in a Child theme, you’ll also have to have some knowledge of Bootstrap’s scaffolding structure. You can get an overview of the different classes used by Bootstrap for structure here: https://twitter.github.io/bootstrap/scaffolding.html
If you add a new widget area and set it to 980px width, it’ll affect the responsiveness of the theme, unless you apply it as a max-width. Having said that, knowledge of CSS is really a necessity, and making use of the various @media queries in this theme will keep things responsive. But, familiarity with the different Bootstrap classes, is probably more important. It’ll save a lot of headaches.
Oh, and you’ll probably add your new widget area to the front page template of your choosing, this theme has a couple – full width, left side-bar, right side-bar. If you use the default template, you’ll want to use a WordPress conditional tag – is_front_page().