It pretty much operates like Facebook if ya have that. Otherwise, you click on the bar at the bottom of the page and it will tell you which of your friends are "online" (green dot) and which ones are not. You then click on their name and a chat window comes up where you can shoot the shit if you so desire.
If you don't want to use this, go to Accounts at the top of the page and there is an option somewhere to disable the chat bar.
Yeah, I was wondering that too SaNNdy - although I was in India last year and I noticed that a lot of the women there have them on their foreheads, so maybe there is some connection.
On the chat bar at the bottom just to the right of the "Who's Online" there is a icon that looks like some kinda nutbob thingamajig. Click on that (Chat Options it's called) and you can change your status options to whatever you'd like.
look at the "Who's Online" icon to the right of the IM toolbar...the little green dot next to the icon indicates that you are online and visible to your friends. If you set your IM status to busy, it shows red, switch to the offline or invisible status and it's grey.