How to add friends on steam?

Does anyone know how I can add friends on steam? Thanks,
Answer #1
or shift+tab ingame
Answer #2
But I mean if you haven’t got a game from steam. The feature is disabled.
Answer #3
But I mean if you haven't got a game from steam. The feature is disabled.
No it’s not.
Answer #4
http://img691.imageshack.us/i/steamcantaddfriend.png/
Answer #5
Wtf? Never encountered that before, even when I had no games at all…
Answer #6
Well, I think Steam made it so people who actually got games off of steam can add friends. Is there any workaround?