Click on "Create an event"
Name the appointment and add your guest. You can also invite your guest after the appointment has been created
Continue creating the appointment by adding date and place options
Click on "Send this event" (or "Create this event" if you haven't chosen a guest yet)
If you didn't choose your guest when creating the appointment, you can send the appointment invitation yourself using the appointment link.
On the appointment page you've just created, click on the "More" button at the top left of the page
Click on "Share this event"
Copy the second link ("Organize an appointment with 1 person only")
Share the link with the person you wish to have a 1-to-1 appointment with