How to Setup iCloud on Your Mac
With iCloud, you can sync your Mac files with your iPhone, iPad, and iPod Touch and make those files available whenever you need them. You were prompted to set up iCloud when you started using your Mac, via a new or existing Apple ID account. But if you refrained from doing so at the time, it's by no means too late to do so.
In the Internet & Wireless section of System Preferences, select iCloud.
You're prompted for your Apple ID.
Enter your Apple ID in the fields provided.
If you don't have an Apple ID yet, click Create an Apple ID. You'll have to provide your location and birthday to establish an Apple ID.
Decide whether to accept the defaults to "Use iCloud for contacts, calendars, reminders, notes and Safari," as well as to "Use Find My Mac." Click Next.
Most likely, you won't want to deselect any of the defaults. Besides, you can always change your mind later, and as you see in the next step, you can check or deselect iCloud options for specific apps and features.
Click the check boxes to select the items you want to use with iCloud — Contacts, Calendars & Reminders, Safari, and so on.
Scroll down to see more options. If all went according to plan, your contacts and calendars, mail, notes, reminders, and so on will turn up at iCloud.com. It's not a bad idea to log on to make sure.