How do you increase the width of header in BP Columns theme?

I would like to increase the width of the blue header image at the top of my site (BP Columns theme) – http://theifhl.com/ – How do I do that?

I would like for the width to be as wide as the site… just like the red buddypress header image at the top of buddypress.org

Note: I'm new to wordpress and buddypress so I will appreciate simple and easy instructions.

Thanks,
Tony