How to add a box around some text?

Hi,

Sorry, but im pretty new to CSS and i need some help. I have searched the web for hours, but i have no idea which way to go!

I need to add a standard box (with grey borders and white background) to a site of mine.

My problem are, that I have no idea where to type in the info about the "box", because there are no individual rules or ID regarding the place i want the frame (or box).

So what I need - please - are someone who can point me in a direction of where I can find some info regaring adding a frame (or whatever) so I can add some properties, like padding, borders etc.

If I select the place I want to get "boxed" it just refeered to the first rules in my Global.css stylesheet.

Hope it makes sence and sorry about my spelling.

Link to the place: http://www.fitdeck.dk/dk/blog/3-core-traening-for-begyndere

The box I would like (made in paint - not to scale) : http://www.fitdeck.dk/img/eksempel.png

Thanks - Tue Nielsen

PS: The box have to appear on all /dk/blog sites.