Certificate installation for Firefox is similar on all operating systems. Let's review the process on OS Windows as an example.
Open the Firefox browser settings by clicking the three lines icon in the top-right corner and selecting Settings from the drop-down menu:
Figure 21 - Entering Settings page
Locate the Certificates section under Privacy & Security and click the View Certificates button:
Figure 22 - The Certificates section
Click the Import button and navigate to the downloaded PEM certificate file:
Figure 23 - The list of installed certificates
Figure 24 - Selecting the certificate file
Check the box next to "Trust this CA to identify websites", then click OK:
Figure 25 - Confirming the trust settings
The certificate is successfully installed.