When your network was initially created, it was set to have its stats and logs disabled. Navigate to the "Settings" tab for the network that you would like to enable statistics for.
Click the "Stats and Logs" button, which will bring you to a screen like the one below.
Make sure that the check box next to "Enable Stats and Logs" is checked. You can also specify whether you would like to receive email updates about your OpenDNS traffic as well. Hitting the Apply button will ensure that your changes will be saved.
Now when you select the "Stats" tab for your network, you will be brought to a dashboard interface containing graphs and charts with the OpenDNS activity that has happened in the last 24 hours or so. You have the option to view detailed graphs of unique domain hits, unique IPs, Blocked Domains and how manytimes they were accessed, as well as bypass logs for your network.