This works for generating CSR files required by GoDaddy SSL certificates. This will work with more than just GoDaddy SSL certificates, you can even sign your own certificates.
In the Terminal application, type:
$ openssl genrsa -des3 -out domain.key 2048
You will now have to enter a passphrase, so type:
$ openssl req -new -key domain.key -out domain.csr
You will now have to re-enter your passphrase to confirm, and then you will be prompted to enter all your information.
During registration, enter the domain name you are registering this certificate for, when prompted:
Common Name (eg, YOUR name) 
You will now have the CSR file you need to send to the signing authority to issue you your certificate.
Here is the code to generate the CRT file ( if you’re not using GoDaddy and you want to sign your own )
openssl x509 -req -days 365 -in domain.csr -signkey domain.key -out domain.crt