ربما يكون لديه مشكلة فى الماسنجر

well, this is actually very simple.
you use the chat window, only when you have selected someone to chat. this person must be on line,of course. so you select the person you want to chat with, look into his/her profile and click on the link chat now.
it pops up the chat window and there you can chat with this person. if you want to chat with someone else, you get back the italki page, look for the other person, click on chat now again and then, the same page that appeared before appears again with the different people you contacted on the left side and the person you are chatting with currently in the left.
you may change the person you talk to whenever you want, you can change them anytime and, the best thing is that you can live messages there and keep your conversations of previous days.
i hope this is useful to you!! bye

aaah, and when you see the icon is moving, i mean like changing the color, and trying to call you atention, is that someone is leaving you or possibly left you a message, so you openthere and chek, that`s it, good nite.