The ssl configuration is in the vhost file of the website, so ther is no additional file added in /etc/httpd/conf/sites-enabled/
Regarding the ssl creation, you have to create a cert first and not paste any other cert there as the private ssl key is missing then and apache is not able to use this cert.
So step 4 is: enter the details for the cert, select "create" as action and click on save.
5) a few minutes later, go to the ssl tab and take the csr that has been created and let it sign by a ssl authority.
6) Take the ssl cert and bundle that you got back from the ssl authority and paste it into the fields in ispconfug, select "save certificate" as action and click on save.