In the Calendar app, you can send meeting and event invitations. iCloud, Microsoft Exchange, and some CalDAV servers also let you send meeting invitations. (Not all calendar servers support every feature.)
Before you can invite people to events you’ve scheduled, you need to make sure your calendar accounts are turned on.
Go to Settings on your iPad.
Tap the event, then tap Edit.
Tap Show As, then tap Free.
You can email all attendees of an event—for example, to share event details.
Go to the Calendar app Reply to invitations in Calendar on iPad