Edit Protean to go full screen

Sorry if this has been asked . I have looked on the forum. I'm new to UNA, I have setup my website using Protean (The template that comes as default) on my own server, I'm just trying to change a few settings within the template. I'm using the 3 column design but it doesn't stretch to use the whole screen is there a way to make it fit and use the whole screen with the centre column bigger then the 2 outside columns?