Accounts list
A list of all your calendar accounts. To see options for an account, select it.
Account Information
Contains a description of your account, which is used as the account’s name in Calendar. It also contains your user information or an Edit Account button to get to the information.
Set how often your account is refreshed. If Push is available, it updates the account when you make a change on any of your devices that use the same account, or when someone makes a change to a shared calendar in that account.
If your account has Availability options, use them to set when you can be invited to events.
Server Settings
If the pane is available, it contains the account’s server address and any other server options.
Delegation
If the pane is available, it allows you to share calendar accounts. To share your account, click Edit, then click the Add button 
.