Please follow the steps below to generate your Certificate Signing Request (CSR) with ISPConfig :
1. Log into your Plesk administration interface as Administrator and click on Server Administration.
2. Click on the Certificates menu, then click on Add SSL certificate.
3. Complete the form following instructions.
4. Name the certificate and choose a 2048bits key length at least.
5. Click on Request. Plesk will generate a unique private key and your CSR.
Finally, check your Certificate Signing Request (CSR).Buy a cheap SSL certificate