Site Configuration is the area where most of your Site Configuration settings can be found. It's also the area you will need to enter your Download and Support key. Note, if you have purchased a renewal you will get a new D/L and Support key, which you will need to use here, replacing the old expired key.
By default, a new installation of Jomres has the Advanced Site Config option set to No. Once you're ready to start exploring Jomres in depth then you can set this option to Yes.