There are some instructions on this Mozilla page http://www.mozilla.org/projects/security/pki/jss/using_jss.html

If you have questions, I'd try the #security channel on irc

Thanks Verdi for your reply. i have already followed the instructions from the the link http://www.mozilla.org/projects/security/pki/jss/using_jss.html . But they did not worked and java console was showing the same error messages: security: Accessing keys and certificate in Mozilla user profile: null security: JSS is not configured

Then definitely try asking about this in the #security irc channel. He we mainly answer questions about typical Firefox issues. Let me know if you can't get any help there.