You can create and manage calendars for all areas of your life by using the Calendar app on iCloud.com from a Mac or Windows web browser. Changes you make are automatically pushed to your iOS devices and computers where you set up iCloud for Calendar. On your iPhone, iPad, or iPod touch, changes are pushed to your Calendar app. On your Mac, changes are pushed to Calendar (or iCal in OS X v10.7.5), and on your Windows computer, changes are pushed to Microsoft Outlook. No matter which device you use to edit your calendars, the changes are updated everywhere, so you never have to connect your device to your computer to keep your calendars current.
When you use iCloud Calendar, you can easily share your calendars with other iCloud users. For example, you can create a shared calendar called “Kids” to keep family members in the loop about school and weekend activities. For more information, see Share a calendar with others.
Calendar alerts also appear in Notification Center on your iOS devices and Mac computers.
Access iCloud Calendar from a web browser
Go to Apple ID (the one you use with iCloud).
If you’re using another iCloud app, click the app’s name at the top of the iCloud.com window, then click Calendar.
When accessing iCloud Calendar, make sure you use a browser recommended in the Apple Support article iCloud: System requirements.