How to Add Non-iPhone Calendars to Your iPhone
You may have discovered the ease of Google Calendar to share appointments with colleagues, or your company might use MS-Exchange. Your iPhone can access the data from all these remote sources and display it in one place — Calendar. Follow these steps to add calendars to your iPhone:
Tap Settings on the Home screen.
Tap Mail, Contacts, Calendars.
Tap Add Account.
If you already set up an account for mail or contacts, tap the name of the account in the list and then tap the Calendar switch On.
Tap the service you use: Exchange, Google, Yahoo!, or Outlook.com.
The Add Account screen opens.
Filling in the Name field is optional. Type in your e-mail address in the Address field and your password in the Password field. An identity is automatically entered in the Description field, however, you can tap and hold on the text to replace it with something that helps you remember the account, such as work or golf team.
Tap the Next button in the upper right corner.
After your account is verified, a screen opens showing a list of available services.
Tap the Calendars switch On.
Swipe back to the first Mail, Contacts, Calendars settings screen and you now see the added account in the Accounts list and the activated services appear under each account name.
You have to sign in on your iPhone with the same account information you use on your computer to have the same information in both places.