The Invitation page is often used for basic and logistic information -- event name, date, time, location, and directions. You can rename it from Invitation to say whatever you want, in case you're not having an event.
Edit the invitation by clicking the "Edit" button in the top right corner. Then fill in whatever information you'd like to see. Don't worry -- if you don't want to include any of the fields, just leave them blank and they will not appear.