In order for SSL to work, you MUST have a certificate on the server. No Cert, no SSL. There is a private Key in the certificates that is used to encrypt the data in transport.
In the desginer, I don't think there is much you can do to define HTTPS, that is usually done at the IIS level.
When you are doing the install on the server, check the USE HTTPS box, and make sure your certificate Subject matches the URL you plan to use when you publish your projects.
In INETMGR, right click on the Default Website and edit the bindings. Remove the binding for port 80, and add the binding fot HTTPS/443 with the exiting certificate. This will foce all the published projects to be HTTPS.
You can also set SSL per project, but it is a manual process. You can right click on the project Virtual Folder in IIS and under Bindings, you can bind to the SSL cert. You should also remove the Binding to port 80 to prevent users from connecting to the non SSL port.
Rob