Once you check the box in your settings and enter the number of greeter games you want to receive at any one time, save settings, they should then start coming through when you're online here.
The part where it says unavailable:
Where it says 'unavailable' under this box in your settings, that refers to whether you want to receive game challenges.
I want to be a Greeter, but my settings wont allow this saying I am unavailable. I have been a member of chess.com for over one month. Any suggestions?