It should work with drag and drop by dragging a track to the user on the People list on the right.
You can also right-click on a track, Send to, Spotify People, pick a user
Ehm yes, I know how the social component of the client is supposed to work. We were talking about users that don't show up because they have not connected with their facebook account.
So: how do you get a 'spotify:user:x' user in the people list so you can share tracks with that particular user?
If the user has enabled social features, you can just enter "spotify:user:x" in the search-field. But now that you mention it, I realized that user x has to connect to Facebook to enable the social features. That is unfortunate.
I was thinking more of users that one is not a "friend" with on Facebook, but that one still wanted to share music with/see playlists from. Like the spotify:users:spotify company user.
EDIT: After some help, I learned that if one cancels connecting with Facebook, then the social features will be activated without requiring a Facebook account.
So: how do you get a 'spotify:user:x' user in the people list so you can share tracks with that particular user?