You may be lucky enough to be the first person who enters one of the web conferencing rooms.  This gives you first speakers advantage when others enter the room.  If you have something you want people to hear about then being the first person in the room will allow you to do that.  Of course you could always host your own room at some point once you get the hang of it here.  If you find that you are in fact the first person to enter the room and you have something relevant to talk about the best thing to do is wait until someone enters by minimizing the web conference room while moving on to something else.  You’ll hear a signal if you leave your speakers on when someone enters the web conference.  

Of course more often then not there may be a group of  people or just one person in the web conference room when you enter.  I would suggest at first being polite when you enter and listen as well as observe text chat dialogue so you don’t interrupt if there is already an important discussion going on.  Then wait for a polite moment to introduce yourself if you aren’t greeted already when you enter.  You will get furthest ahead if you can acr like you would if you were walking into a room of people who are engaging in conversation.  Once you ‘get it’ you’ll see how it’s a great place to connect with others online