You'll see the CSS classes in the HTML on the skin1/customer/home.tpl
Make your new CSS classes in the skin.css in skin1 and replace the ones you want to change.
Remember CSS is cascading so you can create an ID around the right table column to control any elements inside it.
Good page to learn about CSS methods:
http://hotwired.lycos.com/webmonkey/reference/stylesheet_guide/