The SSL certificate renewal process includes 3 steps:
Generation of the Certificate Signing Request (CSR)
Certificate Signing Request has to be generated for the instance and subdomains you are planning to secure prior to purchasing a certificate. You will need to provide some information required to generate the CSR (such as Common Name, Organization Name and address, etc.). Learn more
Purchase of the SSL certificate
Once the CSR is generated, you can use it to purchase the SSL certificate from the Certificate Authority that your company approves.
Installation of the SSL certificate
Install the purchased SSL certificate on the desired subdomain to secure them. Learn more