Importing Certificate/Signature into Mozilla Firefox

To import a certificate along with the associated private key from a PKCS#12 file (.pfx/.p12) into your Mozilla Firefox web browser:

Launch Mozilla Firefox web browser
Open Tools
Select Options
Switch to Advanced tab
Click the View Certificates button
Switch to Your Certificates tab
Click the Import button
Locate the '.pfx/.p12' file you transported/exported, select it and click Open
Enter the password you created when exporting the certificate
Click OK to complete the certificate import
Your certificate is now installed and it should be visible on the list of your certificates