Firefox 24 free ( full version)
To install the Firefox 25 beta. You need to make sure that the browser was firefox is working.
Then proceed with the installation as usual. (This is a beta, so you can not use the auto update)
Wait one moment to test it:
After completing the above process, restart your browser, then go to the [B] Help> About Firefox [/ B] to see was not updated successfully
Have fun !