In Mozilla Firefox, navigate to the menu icon (≡) in the top right corner of the window. Click on it, then choose "Add-Ons".
Find the extension named NoClickjack, and click the "Enable" button to the right of the name
Once enabled, you should see NoClickjack's blue shield icon in the top right corner of your browser.ccc
Note: You can also install the "NoClickjack" extension by opening the following links in their respective internet browser:
Mozilla Firefox: Install NoClickjack for Mozilla Firefox