Its a great start.. but I feel you have a bit further along the path to travel. My advice would be to centre your website and give the sidebar and main context area 2 distinct zones. Also to remove that divider as it reminds me of old websites that used scrolling boxes for the sidebars S) To kick start you designing here are a few exmaples: blog2life.net fabworker.com psdtuts.com Hope this helps!
Rather than using the vertical adsense banner in you sideabar try a horizontal one above "Welcome to Freepaste.org" There's alot of empty space at the top of the page.