If you have CA installed and have created a certificate through your domain in IIS, then all you have to do is go to your virtual directory and go to properties > the Directory Security tab > click Server Certificate > and go through those steps and it will show you which certificates are created on your server. When you are done, 2 things will happen, 1, the button will be blanked out that says Server Certificate, and 2, you must check the box that says require SSL in the Directory Security tab under Secure communications in the edit button.
Then you go to your virtual directory with https:// instead of http:// and it will come up
Since you made this cert yourself, it will come up and tell you that there is an error. It is still secure, it just shows you that 2 issues are good and 1 is not. The issue that does not show as good, is the fact that you made a cert for the domain name and as a virtual dir it will not have the same identity. It's no big deal though... SSL still works..
Hope that helps