If you would like to use an SSL certificate with a Joomla website, you can enable it via:
Step 1: Login to administrator’s panel
Step 2: Go to Site and then Global Configuration
Step 3: Select Server tab
Step 4: You will find the field “Force SSL”. From a drop down menu you can select between two options:
Administrator only – This option will enable the SSL usage only for your website’s administrative section.
Entire Site – This option will enable the SSL for your entire website including its front area and administrative section.
Note that in order to use an SSL certificate with your Joomla, you will need a Private SSL certificate issued for your domain.