Ok, you have a shiny new website, you have Drupal as a CMS and you have an AdSense account. The only thing you don't have is a clue about why banners are not showing up on your website, even though you copied the AdSense code verbatim into your nodes/blocks.
First of all, let me give you a fair warning: Never put bannercode directly in your content nodes. Doing so will completely undermine the idea of using a CMS in the first place and open you up to all sorts of nasty side effects like for example accidentally showing more then the allowed amount of ads in the teasers of your frontpage. You may want to read this article for some ideas on AdSense integration in Drupal.