If you happen to visit sites with self signed security certificates you will notice a error in firefox saying
This site uses an invalid security certificate.
The certificate is not trusted because it is self signed.
(Error code: sec_error_untrusted_issuer)
Firefox shows this message many times while you browse that site. Fortunately there is a way to add the certificate of that site manually. Here is how to do it.
--- Go to Tools --> Options in the menu bar of firefox.
--- Now click on the Advanced tab
--- Now click on the Certificates tab and then on the View Certificates button.
--- Now click on the Add Exception. You will see the following screen.
Here add the site you want to get the certificate to. Then click on get certificate. Firefox will check for the certificate and show it.
--- Now select Permanently store this exception and then press Confirm Security Exception.
That's it you will no longer get the self signed security certificate error for that site. You can also add other such sites following the above steps.
--- Go to Tools --> Options in the menu bar of firefox.
--- Now click on the Advanced tab
--- Now click on the Certificates tab and then on the View Certificates button.
--- Now click on the Add Exception. You will see the following screen.
Here add the site you want to get the certificate to. Then click on get certificate. Firefox will check for the certificate and show it.
--- Now select Permanently store this exception and then press Confirm Security Exception.
That's it you will no longer get the self signed security certificate error for that site. You can also add other such sites following the above steps.

