Go to the ‘Settings & Schedules’ tab at the top of your page. Then choose ‘Edit Templates’. To create a new template, scroll past your current templates to the ‘+ Create your own Template’ text. Click on this. Choose a base template from the list on the left. Then choose the ‘Great, Now Customize It’ button at the bottom. Add cards, text, or files that you want to show up on every day that you use this template. Then, choose classes and days you want this template to appear. Finally, choose the ‘Finish and return to planbook’ button at the bottom of the modal.
Note: When you update your template Cc only updates blank lessons that you haven't touched yet.