Radicale is a calendar server which allows your to synchronise your calendar across all your devices. Support for CalDAV within various client systems can be quite patchy/flaky though, so use it with caution.
Using cursor keys, space bar and Enter key select *Administrator controls* and type in your password.
Select *Add/Remove Apps* then *radicale*. If you don't already have an SSL/TLS certificate for your main domain then go to the security settings and create a new Let's Encrypt cert for it. That will ensure that your calendar events have some minimal level of protection from passive surveillance.
There seems to be a problem with Let's Encrypt certificates with this app, but it's possible to get around it. Open DAVdroid and select the side *menu* followed by *Settings*. Enable *Distrust system certificates* and press *Reset untrusted certificates*.
Exit from settings and press the *plus button* to add an account. Select *Login with URL and user name*. The URL should be https://yourmaindomainname/radicale/. Remember to include the trailing slash on the URL. If you installed Freedombone from a disk image then enter your username and the password which was shown at the start of installation. If not then the password for Radicale will be within the README file within your home directory.
You will be prompted to approve the Let's Encrypt cerificate for your domain name, and once that's done then you should see your account as a large yellow box. Press on that and ensure that *Addresses* and *calendar* are selected.
Now go to your calendar app and press the plus icon to add an event. You should notice that the calendar account selected is your username on the Freedombone system.
