Open Mozila Firefox and follow the instructions:
In the top right corner of your web browser open the Options menu.
A pop-up settings window will appear. To open the list of personal digital certificates, click Privacy & Security in the right-side menu.
At the bottom of the page, where you can see Certificates, click the View Certificates button.
After clicking on View Certificates, Certificate Manager will open. Go to the Your certificates tab and begin the import process by clicking the Import button.
In the next step, select the file where you saved the digital certificate and finish by clicking on Open.
Upon the receipt of your digital certificate you have set a password. In the next step enter this password in the empty field and continue by clicking on the OK button.
When the password has been entered, the import process is complete. Your digital certificate will be visible in the Your certificates tab. Close the window by clicking on the OK button.