How do I add a Google Calendar to Calendah?
For adding a Google calendar as a Calendah Calendar, go to your Google calendar, click on Settings and Sharing of the calendar you would like to add to Calendah: 
Then click Integrate Calendar and find the Secret address, copy the URL: 
Then go to your Calendah -> Calendars and click Add: 
Next, select External (.ics), and pick Google:

Paste the secret address into File URL and click Validate: 
Done! You can adjust the rest of the settings of your calendar as needed, adding or changing properties you want to show up on a card label and card description, your sharing settings etc.