I keep trying to enable via firefox the UNC Novell upload addon. I keep getting the following error as noted by the documentation.

To avoid this error and download the add-on, you must do the following:

In the Firefox Web browser, open about:config.

Create a boolean preference with the name extensions.install.requireBuiltInCerts and value set to False.

Click the Install the Novell File Upload extension link.

In the browser, open about:config and reset the value of extensions.install.requireBuiltInCerts to True.

Click Install Now, then restart your Web browser.

Where is about:config? I cannot find this. I've even tried IE tab to emulate IE and still it wants me to install this. any help is appreciated. Thanks!