Need to widen my site's sidebar

Hello,

First, I’m loving the theme. Thanks and keep up the good work.

Here’s my issue: I added a facebook widget to the sidebar. Facebook widget minimum size is like 292 pixels. This is not fitting in my sidebar – it overlaps with my site’s background image. How can I widen my sidebar slightly to allow the facebook widget to fit properly?

My site: MammothTourism.com

I’ve already got a child theme set up, so if you are able, I would love instructions on exactly how to modify my child theme to achieve what I’m hoping to do.

Thanks!
Paul