Cut and paste your adsense script between the list element tags in the sidebar-left.php theme file for great performing Google adsense ads. Even easier, create a text widget for Sidebar 2 and cut and paste your code in the text widget. That way you never have to touch a line of theme code!
You can put anything here, such as author information or any other text. Even easier, add a text widget to Sidebar 2. That way you don't need to touch this code.