cranky_geek's dashboard

how do i chat to other people?
I see other people in the map....but im not sure how to start a convo...
Earlier you had mentioned to use the shoutout tab....I been trying to find that tab...but i cant find it....can someone help me out? also I would like to know, what exactly is the purpose of medium?..and I have been trying to find some online documentation to know and understand medium but all i got was a shockwave tutorial..