Your control panel is cPanel.
When you're logged into the Blesta admin, go to Settings and click on the System Tab. Click on 'Automation' and grab the cron code there. Next, login to cPanel and go to the cron section. You'll enter that code but make the change mentioned in this article from licensecart: https://licensecart.com/billing/plugin/support_manager/knowledgebase/view/206/cron-job-isn-t-working/10/