The simplest way to get advertisements up and running in your community is to activate Google AdSense through your admin panel (monetize).
Please see www.google.com/adsense for details
You can alternatively copy the HTML code provided to you by another ad company into a new block.
Please see: https://www.google.com/adsense/v3/signup?utm_content=nsufv1
We have a tutorial video for you: http://screencast.com/t/rM6snXhDaTN see this video to learn, how to sign up for Google AdSense
Check out this screenshot to set up Google AdSense Codes correctly