Click the Folders link to open the Mailboxes page. This page displays your Mailboxes, and it allows you to open an existing Mailbox or to create a new one:
To open a Mailbox, click on its name.
Some Mailboxes are "unselectable" and their names are not URL links.
You can open the Settings page and specify which Mailboxes should be displayed in the Mailboxes page:
Display All Account Mailboxes
Display Subscribed Mailboxes
To create a Mailbox, select the Mailbox type (regular Mailbox, AddressBook, Calendar, etc.) and type in the new Mailbox name, then click the Create button.