If you already have your SSL Certificate and need to install it, see Webmin SSL Certificate Installation.
How to generate a CSR for Webmin
We recommend that you save some time by using our OpenSSL CSR Wizard. Just fill in the details, click Generate, and paste your customized OpenSSL command into your terminal. Save the private key that the command generated and open the Certificate Signing Request (CSR) in a text editor so you can paste it in the SSL ordering process.
If you prefer to build your shell commands, follow our generic instructions for OpenSSL CSR creation.
After you receive your SSL Certificate from DigiCert, you can install it.
See Webmin SSL Certificate Installation.