How do I create border around site

Hi,

I wish to add a border on the left and right side of my site.
Here’s site: http://www.informationmarketingexpert.com/test/
I placed css here so you can see: http://www.informationmarketingexpert.com/styletest.css

I use Mspaint to show you where I want the border:
http://www.informationmarketingexpert.com/bordereg.jpg

Can you please tell me what code to input and where in the css file to make this border?

Thanks