First, what you need to do, if you have never worked with wordpress before, is to find a template for wordpress themes, this will make your live a lot easier.

I made one for you so you can download it from here: WPGeek WordPress Template (You can do with it whatever you want)

There you will need to fill style.css file with colors and/or images, add paddings/margins and borders where you want and you get yourself a Custom Wordpress Theme. This template is 3 columns, fixed width: 1000px, center aligned and sidebar widgetized.