Here for a meeting? You'll need to be a member of the community and make sure you're logged in. (You can sign up here.) Go to the Online Meetings page for the current chat schedule. (Navy MORE participants, click here!)
Next, find your room by clicking on the "Groups" tab below. Click on the room you want, and you'll be in the meeting. Say hi; if anyone else is in the room they'll greet you.
Not here for a meeting and just want to hang out? You can try the Open Chat room to see if anyone is around.