Drupals Themes and Templates
When first getting drupal installed you have a basic looking site, with more function than a normal site of course. The look and feel of the site is determined by the sites template or in Drupals case its theme. The reason they call it a theme (this is an opinion) is that each theme has several template files in it, made up of a mixture of php and html. Plus they will have a stlyle sheet. Calling a theme a template might confuse the template files with the full on theme of a site.
Your out of the box install comes with several themes, mostly plain looking but not bad and the default theme is garland. So if you want to make a quick overhall to the look of your site you simply need to head over to your admin theme section and choose a different theme.
You could always design your own template/theme or take a quick look at the drupal community sites they have plenty of them, most of them for free. There is a fairly new site out as well that has tons of free drupal themes. It has a bunch to choose from all free and no back link (on the bottom) required. Anyways the point is that with a few quick searches you can have a great looking site simply by changing drupals themes.