Select the Firefox Preferences menu item.
Click on the Advanced tab.
Click on the Encryption tab in the advanced section.
Click on the View Certificates button.
Under the Your Certificate tab, select the certificate to export.
Click on the Backup button to export the private key, its corresponding certificate, and signing chain certificates into a file.
Enter a file name, select a location, and save it as a PKCS#12 file. PKCS#12 is a format for storing private keys and certificates.
The Certificate Manager will prompt you for a password to protect the private key in the PKCS#12 file. Enter a strong password and press OK.
The private key, its corresponding certificate, and the certificates in the signing chain are exported to the backup file.
Close the Certificate Manager window and the Preferences window.