Generate a CSR:

openssl req -new -newkey rsa:2048 -nodes -sha256 -out wildcard.domain.fqdn.csr -keyout wildcard.domain.fqdn.key -subj "/C=your_country/ST=your_state/L=your_city/O=your_organization/CN=*.domain.fqdn"

View the CSR:

openssl req -text -in wildcard.domain.fqdn.csr

Sign the certificate:

openssl ca -in wildcard.domain.fqdn.csr -out wildcard.domain.fqdn.cer -config /path/to/openssl.cnf

Convert the certificate to PFX:

openssl pkcs12 -export -out wildcard.domain.fqdn.pfx -inkey wildcard.domain.fqdn.key -in wildcard.domain.fqdn.cer

Covert the certificate to PEM:

openssl pkcs12 -in wildcard.domain.fqdn.pfx -out wildcard.domain.fqdn.pem -nodes