This is the answers of group seneca8:
* What is a Firefox Extension?
* What is a Firefox Theme? A theme is a customization of the look and feel of the browser. For example, a theme can change the default colours and the icons used for the buttons.
* How to get and install Firefox add-ons. We can get Firefox add-ons from the website: https://addons.mozilla.org/ Search and choose you want. For example, I found an add-on named "Download Statusbar": https://addons.mozilla.org/firefox/26/ I want to install, just click the button "Install Now",
* List and describe as many extensions/themes as you can -Chatzilla: An IRC chat client for a community to discuss any issues. -DOM Inspector: Inspect the DOM of HTML, XUL, and XML pages, including the mail chrome. -Adblock: Gives the user to remove unwanted web page ads in the future browsing. -Download Statusbar: replaces the popup download window with a status bar notification.