Install the plugin, check the extension list and pin it to the toolbar. Then, simply click on the icon in the toolbar to edit. Click again to blur and click once more to disable edit/blur mode. Easy peasy!

it doesn't show up in my extension drawer at all, so I can't use it? it's installed and active, but I can't find it anywhere in my browser itself.

It's fun, it's practical. It's used in some situations