ProCon is a content filter for the Firefox browser created by Corvineum. This might be the button that you are looking for.
If you are just looking to just filter out advertising images and banners then you should consider a filter subscription such as Adblock Plus. This addon is easy to install and update.
Well done for choosing Mozilla Firefox :-)
You can block websites for all browsers using your HOSTS file. See the link below to learn how.
Use blocksite you can get it from the mozilla/firefox website. Or click tools/add-ons/ get extensions to take you there and do a search for the add on.