If you use Firefox as your Internet browser and want to block websites from being viewed, you can install a free third-party add-on called BlockSite. With this add-on, you can make a list of websites that you want blocked in your browser. BlockSite also has a password protection eature that helps prevent unwanted changes to BlockSite by others.
Step One: Launch your Firefox Web browser. Click “Tools” then “Add-ons.” Click “Get Add-ons”. Type “blocksite” in the search bar after the Mozilla Firefox add-ons website opens and hit “Enter.”
Step Two: Find the proper one and click “Install” to install the application. Restart Firefox when prompted after installing.
Step Three: Find BlockSite in your list of Add-ons and click on the “Options” button. Make sure the “Blacklist” radio button is checked, as well as “Enable BlockSite,” “Enable warning messages” and “Enable link removal.” Check “Enable authentication” and enter a password if you would like to keep other users from changing the settings without your permission.
Step Four: Click the “Add” button, type or copy the URL of the website you would like to block in the text box, and click “OK.”