Purchase the cert
Prior to purchasing a cert, you need to generate a private key, and a CSR file (Certificate Signing Request). You'll be asked for the content of the CSR file when ordering the certificate.
openssl req -new -newkey rsa:2048 -nodes -keyout example_com.key -out example_com.csr
This gives you two files:
- example_com.key -- your Private key. You'll need this later to configure ngxinx.