Invite guests to your event
Guests who use Google Calendar will receive an invitation based on their own notification settings.
Google Calendar lets you create invitations for special events, send those invitations to friends, and keep track of responses and comments all in one place.
To invite someone to your event, just follow these steps:
Click on the event (or create a new event) and select Edit event details (alternatively, you can click on the event's name to open the event details page).
In the Guests section on the right, enter the email address of each of your guests and click Add. You'll see each guest appear under the "Guests" section below.
Select the appropriate options for your guests under the "Guests can" section.
In the Send invitations? pop-up window that appears, click Send if you'd like to notify your guests of the event; if you do not want to notify your guests, click Don't send.
Google Apps Users: You can invite one or more groups to your event by following the steps described above. Please review some Apps specific guidelines that are in place when inviting groups.