When installed, an SSL Certificate will activate the https protocol and allow secure connections from a web server to a browser. It will replace the "not secure" message in your browser with a padlock symbol. If you are a Standard Plan or Plus Plan user with WebsiteBox you will have at least 1 SSL Certificate built in to your account (Standard = 1, Plus = 5). Your SSL Certificate(s) can be enabled from within the DOMAINS App on your dashboard.
Navigate to the Domains App, then click on the domain name you want to secure. This will open up your domain settings. Make sure that your website has been published to this domain already.
Look for the line of information with the Host Name: www - there will be an ON/OFF switch here, labelled "ENABLE SSL?" Click this switch, then wait a few seconds for it to activate.
Once enabled, your website will start to show as secure online within the next 10 - 15 minutes.