Your Windows Calendar is a part of the Microsoft Outlook productivity program. This valuable computer program allows you to keep track of important dates and set reminders for yourself so you don't forget things. By using the iTunes music management software, you can sync your Windows Calendar to the "Calendar" application that is built into your Apple iPhone.
Connect your iPhone to your computer.
Click on your iPhone's name from the "Devices" listing in iTunes.
Click on the "Info" tab.
Click "Sync Contacts." Select "Windows Contacts" from the drop down menu on this portion of the screen. This will inform the iTunes software that you want to transfer all of the data on your computer associated with Microsoft Outlook/Windows Mail accounts, including the calendar information, to your iPhone. Click the "Sync" button to transfer these calendar entries to your iPhone "Calendar" application.