How to Manage Your iCloud Storage
Apple knows that you’re curious about how much space you’ve taken up in your personal iCloud. To monitor your iCloud storage, click the Manage button at the bottom-right corner of the iCloud Preferences pane. From the sheet that appears, you can see how much space you’re using for document and data storage.
Click the data type in the left column, and iCloud displays the amount of storage space that’s being used for that data. Other items that might appear in this sheet include Mail and selected iPad and iPhone apps that support iCloud.
If you find yourself running out of iCloud storage space, delete any stored item by selecting it in the list at the right side of the sheet and then clicking Delete.
If you need more elbow room than the default (free) 5GB than Apple provides, Apple is happy to provide you with an additional 10GB, 20GB, or even 50GB of storage for an annual subscription fee of $20, $40, or $100 per year, respectively. Click the Manage button on the iCloud pane in System Preferences and then click the Buy More Storage button.