Firebug for wordpress 3.5.1

Firebug has nothing to do with WordPress – it may have to do with your Operating System. What version of Firefox are you using and what OS?

To see and modify css function I want to use firebug. I am using firefox 22.0 amd OS is Windows XP.

Try seeking help from Mozilla: https://support.mozilla.org/en-US/home

OK, I will try.