Find My is not working on my new Mac Mini2

I have an iPhone where "find my friends" etc. works perfectly. Recently I bought a Mac mini 2 and I am cannot set up Find My on the desktop application.

If I go to the Find My App, it only says:

The instructions from there are not clear. how do I set up find my friends, find my Mac etc.

Looking at some of the other posts on find my, I am supposed to see a list of friends that I need to select from. How do I get there?

Thanks