Certbot - how to manually install certs?

Thanks for your help. random.com was just an example. its actually tourismstcatharines.ca. What you provided was exactly what I needed but it still does not work for me. When I set Apache to use the .pem files I still get the browser warning - “Warning: Potential Security Risk Ahead”.
In fact this is why I’m trying to use Certbot, because the certs from sslforfree.com started doing this same thing. I’m doing something wrong all of a sudden, but theres nothing different.

Do you know why this is happening? Do I have to choose a different web server when setting up certbot? I chose Apache.