When Firefox 3.x attempts to connect with secure https to a site which has self-signed or expired SSL certificates, it will show an exception box saying that there is a problem with the certificate.  To accept the certificates for the slte:

1. Click on the link Or you can add an exception link at the bottom of the box
2. This will add a section at the bottom of the box that looks like this:
3. Click on the Add Exception link
4. Click on the Get Certificate Link
5. Click on the Confirm Security Exception button