Generate a Private Key with OpenSSL
openssl genrsa -out wildcard.jasonosull.com.key 2048
Then generate your CSR from the Private Key
openssl req -new -key wildcard.jasonosull.com.key -out wildcard.jasonosull.com.csr
You will then be asked a series of questions about your Organisation, State/location and a Common Name (CN)
Or you can use the one liner and fill the information
openssl req -new -newkey rsa:2048 -nodes -keyout wildcard.jasonosull.com.key -out wildcard.jasonosull.com.csr -subj "/C=IE/ST=Leinster/L=Dublin/O=Jasonosull Inc/OU=IT/CN=*.jasonosull.com"
Verify Your Certificate Request,
openssl req -in wildcard.jasonosull.com.csr -noout -text