link to add-on https://addons.mozilla.org/en-US/firefox/addon/web-editor/
WebEditor is a Mozilla Firefox addon , which let you make any webpage editable ,
It injects a specific javascript code in the page to make it editable .
*install the addon. *open any webpage (It will not work on Mozilla local Webpages) *Then click on the addon button , *Now you will see an alert box , "stating editor mode started" , *Now you can edit site as per our requirement *then save it *using CTRL + S