I´VE NEVER CHATTED HERE, DANNY, BUT I HAVE JUST TRIED TO BECAUSE I SAY ANGIE WU IS ONLINE. BUT SHE DOESN´T ANSWER, SO I DON´T KNOW IF I´M DOING IT RIGHT. I CAN´T ACCESS HER PROFILE EITHER, TO SEE IF IT HAS A PHONE NUMBER.
When you move your mouse over my thumbnail, that little photo, a little additional menu opens up. There's an option to write a chat message at the bottom of this menu. When you write it and click to send, the chat window opens up on the bottom panel, just like in Facebook. Ok, try it with Angie, not me.
When you start chatting with someone, it's like in Facebook, a strip with your name appears in the bottom panel blinking, showing that the other one received a new chat message. Clicking on it will open a standard chat window (I suggest you try it between you and your sister just to see how it behaves). And if Angie was already offline, it should send her an email notification about a new chat message.
By the way, I'm planning on adding sounds to chat so when you receive a new message you will hear the sound alert too - which may not be helpful if you turn your sound off, though (like me).