with directory plugin, want to center posts and make 6 of them show up, not 5

Ive got my homepage setup to display most recent posts. i have more then 6 categories (what are showing up instead of posts since i have no posts), but only 5 are showing up. also, they are a bit left of center, and i would like them centered on the page. would also like to center the actual words within the separate boxes, and change their color when being hovered on. Where can i go to get these things done? the website is http://www.restaurantcaloriecounter.org

thanks!