打开火狐浏览器。 前往“Disable Private Browsing Plus”插件页面。 单击添加到Firefox。 单击 安装。 单击立刻重启。

Given the above summary, write a detailed text in English for it.
Firefox is a blue app with an orange fox encircling it. You can find it at https://addons.mozilla.org/en-US/firefox/addon/disable-private-browsing-pl/. Doing so will prompt a pop-up menu in the top-left corner of the page. It's in the pop-up menu. Firefox will install the plugin, close, and then restart; once this process is complete, you will no longer be able to access private browsing.  You will first need to click Start in Safe Mode if prompted to do so. This plugin disables history deleting. You also won't be able to delete bookmarks with this plugin active.