Click on 'Pages' to open a previously created Playbook, or press the 'Add Playbook' button (the '+' button on the far right side of the top header) to begin a new one:
(You can also switch between different seasons' Playbooks by clicking on the season listed in the upper left hand corner of the screen)
You will begin with a blank page. You can start work right away, or can add a template to the page to work on via the 'Page Background' box on the right side of the screen:
You can 'Add Pages' as you go via the 'Add Page' button on left side of the page. You can also drag and drop your different Playbook pages into the sequential order you prefer.