Get startetd with contacts and shared addresses

Hey there,
I will cut my ropes to google a bit more and installed nextcloud.
I’ve already moved my calendars and it work like a charm to use them (private and shared-ones).

I’ve found that you can create circles. I’ve made it, but don’t see how to use it at least.

Does I miss it, or is there a leak of detailed documentation for many nextcloud-apps?

Any help is really appreciated.