How do I create/renew an SSL certificate?

There are a couple of ways you can obtain a new SSL certificate, depending on whether you need it for private use or commercial use. The easiest way is typically by using LetsEncrypt. We have instructions for creating a self-signed TLS certificate available here. Self-signed certificates are ideal for personal or internal use and can be configured to work with Apache or with Nginx. If you are in need of a commercial certificate for a publicly available website, we have instructions for obtaining one available here. You can also use cPanel to obtain a commercially-signed TLS certificate if you use it.

You'll see references to both SSL and TLS in these documents. They are both protocols for secure access; SSL is the predecessor to TLS.