Our volunteers are working on translating this article. Until it's ready, maybe the English version can be of some help.
It is often important to know which version of Firefox you are using. You can find out which version you are using in the About Mozilla Firefox window.
To access this window:
At the top of the Firefox window, click the Firefox button, go over to the Help menu and select About Firefox. For Windows XP: Go to the Help menu and select About Firefox.On the menu bar, click the Firefox menu and select About Firefox.At the top of the Firefox window, click the Help menu and select About Firefox.
The About Mozilla Firefox window will appear. Your version number is listed underneath the Firefox name.
Note: Opening the About Mozilla Firefox window will, by default, start an update check to see if an updated version of Firefox is available. For more information, see Update Firefox to the latest version.