Simple Border

I am using Antisnews theme on my wordpress blog, and I would like to put a black border 5pix around the entire page.

I’m not sure if this is the correct category to post this question in, but I have not idea how to do this, or where to start.

I apologize if this has already been asked and explained, I searched the forums here, but only found issues for removing borders, and small borders within the page as opposed to around the entire page.

Maybe someone can point me in the right direction?

Thanks,

Valerie