For Seniors: Subscribe to and Share Calendars on iPhone 4S
If you use a calendar available from an online service such as Yahoo! or Google, you can subscribe to that calendar to read events saved there on your iPhone 4S. Note that you can only read, not edit, these events.
Tap the Settings icon on the Home screen to get started. Tap the Mail, Contacts, Calendars option.
The Mail, Contacts, Calendars settings pane appears.
Tap Add Account.
The Add Account options appear.
Tap an e-mail choice, such as Gmail or Yahoo!.
A dialog box appears.
Enter your name, e-mail address, and e-mail account password.
Tap Save. iPhone verifies your address.
Tap the Fetch New Data option in the Mail, Contacts, Calendars dialog.
Your iPhone retrieves data from your calendar at the interval you have set to fetch data. Review these settings.
In the Fetch New Data dialog that appears, be sure that the Push option’s On/Off button reads On.
Choose the option you prefer for how frequently data is pushed to your iPhone.
If you use Microsoft Outlook's calendar or iCal on your main computer, you can sync it to your iPhone calendar to avoid having to reenter event information. To do this, use iCloud settings to sync automatically or connect your iPhone to your computer with the Dock Connector to USB Cable and use settings in your iTunes account to sync with calendars — or use Wi-Fi syncing if you eschew cables.
Click the Sync button, and your calendar settings will be shared between your computer and iPhone (in both directions).
If you store birthdays for people in the Contacts app, the Calendar app then displays these when the day comes around so you won’t forget to pass on your congratulations!
Though you can have calendar events pushed to you or synced from multiple e-mail accounts, remember that having data pushed to your iPhone may drain your battery more quickly.