I’m sorry, but installing the SSL certificate isn’t the final step. Installing an SSL certificate only makes your website capable of using HTTPS. It doesn’t automatically mean everyone will actually start using it.
That’s good, because most websites require some additional changes before they work properly on HTTPS. We could (theoretically) force HTTPS by default when you install the certificate, but doing so will break many sites, which is entirely unnecessary.
You’ll need to manually update your website configured to use HTTPS URLs (if necessary), and setup some way to force all traffic to the HTTPS version of your site.