re:
From within the the Calendars app, do the following:
1. Select "Calendars". Afterwards, if you have more than one calendar configured, they will all be listed.
2. Tap on the circle with an i next to the calendar you want to share.
3. Under the "Share With" section, select "Add Person".
4. Enter the name or email address of the person you want to share the calendar with.
5. Select "Add".