how do we put up parental ratings, in order to filter out adult rated content?

There are several addons you may use with Firefox and Firefox for android for parental control. Some of them: * https://addons.mozilla.org/EN-us/firefox/addon/foxfilter/ * https://addons.mozilla.org/en-us/firefox/addon/webfilter/ * https://addons.mozilla.org/en-us/firefox/addon/adult-blocker/