If you want to see the plans you've confirmed in your personal calendar, subscribe to the Services calendar. The plan times are added to your personal calendar for you to view, but you cannot edit the calendar event.
When you subscribe to your Services calendar, the event information is pulled into your personal calendar, and you cannot edit those events in your personal calendar. However, you can add notes or invite others to the event:
From iCal, click the link to view the plan that you are scheduled for.