Adblocking should already be enabled for you using the Easylist adblock subscription. You can further configure it by clicking on the configuration menu button and choosing → to open Ad Block Settings dialog. Click on Manual Filters. Here, you can add custom filters using wildcard strings (e.g. http://www.site.com/ads/*) or regular expressions within forward slashes (e.g.
Clicking OK activates your adblock filters instantly.